ITMI20111662A1 - PLANT AND PROCEDURE TO RECYCLE PLASTERBOARD PANELS AND SIMILAR CONSTRUCTION MATERIALS - Google Patents

Description

PLANT AND PROCEDURE FOR RECYCLING PANELS OF

PLASTERBOARD AND SIMILAR BUILDING MATERIALS

Field of invention

[1] The present invention relates to a plant and a process for recycling plasterboard panels and similar building materials, in particular plasterboard panels coupled to layers of paper, cardboard, fabric or plastic.

State of the art

[2] The plants currently known for recycling plasterboard panels have the defect of shredding the sheets of paper or cardboard that cover the rear face of the panels themselves; this makes it more difficult to subsequently separate the paper and cardboard from the plaster.

Another defect of the plants known to recycle plasterboard is that they are fixed on the place of operation, and of large dimensions, with an average production capacity of about 80 m ^ 3 / h (about 3 tons / hour) and an average cost around to 2,000,000 Euros.

[3] This means that until today large quantities of plasterboard panels resulting from demolition or renovation of buildings are disposed of, at least in Italy, approximately 90% in common landfills for special non-hazardous waste, while only the remaining 10% is disposed of in cement factories. On the one hand, this involves a great risk of soil and groundwater pollution, in particular by sulphates; on the other hand it constitutes a loss of enormous quantities of gypsum which could be more profitably recovered. In fact, it is estimated that around 80 million tons of gypsum panels are produced each year worldwide, of which approximately 85% in the United States, Japan and Europe. In Italy, the production and sale of plasterboard is currently growing. Also worldwide, it is estimated that approximately 15 million tons of drywall waste are disposed of in landfills every year. An increase in recycled plasterboard would also reduce the environmental impact of the extraction of raw gypsum from quarries, which for example in Italy is currently 2,400,000 tons / year.

[4] A first purpose of the present invention is to obviate the aforementioned drawbacks and in particular that of providing a plant and a process for recycling plasterboard panels and similar building materials, which allows to recover a greater fraction of gypsum from the recycled panels .

A second object of the present invention is to provide a plant and a process for recycling plasterboard panels and similar building materials which are more efficient than known plants and processes.

Summary of the invention

[5] This object, in a first aspect of the invention is achieved with a plant for recycling plasterboard panels and similar building materials, having the characteristics according to claim 1.

In a second aspect of the invention, this object is achieved with a process for recycling plasterboard panels and similar building materials, having the characteristics according to claim 14.

[6] Further characteristics of the device are the subject of the dependent claims.

The advantages achievable with the present invention will become more evident to the skilled in the art from the following detailed description of some particular non-limiting examples of embodiment, illustrated with reference to the following schematic figures.

List of Figures

Figure 1 shows a side view of a plant for recycling plasterboard panels, according to a first embodiment of the invention, in operating conditions;

Figure 2 shows a first section of the hammer mill of the plant of Figure 1, according to the plane of section II-II perpendicular to the rotation axis of the rotor of the mill itself;

Figure 3 shows a second section of the hammer mill of the plant of Figure 1, according to the section plane III-III parallel to the axis of rotation A of the rotor of the mill itself;

Figure 4 shows, in lateral view, the piston feeder of the implant of Figure 1;

Figure 5 shows a top view of the plant of Figure 1;

Figure 6 shows a side view of the plant of Figure 1, disassembled, folded and loaded on a truck for transport;

Figure 7 shows a detail of a section of a hammer mill according to a second embodiment of the invention, according to a section plane perpendicular to the rotation axis of the mill rotor.

Detailed description

[7] Figures 1-6 relate to a plant for recycling plasterboard panels and similar building materials according to a first particular embodiment of the invention. This system, indicated with the overall reference 1, comprises a supporting frame or carcass preferably mounted on motorized wheels or tracks 3 so as to be self-propelled and to be able to move at a maximum speed equal to or greater than 10 km / h, more preferably equal to or greater than 30 km / h and even more preferably equal to or greater than 60 km / h, in order to make autonomous movements of the system 1 economically convenient, i.e. without towing it with external tractors, approximately in the order of tens or hundreds of meters, or even several kilometers. A hopper 5 is preferably mounted on the supporting frame or carcass and is designed to receive the plasterboard panels, or their fragments, to be treated. A heat engine 35 is preferably present on the supporting frame or casing to supply the power necessary to make the system work and move it.

[8] According to one aspect of the invention, plant 1 is equipped with a hammer mill 7, which in turn includes:

- a crushing chamber 9;

-a rotor 11 mounted inside the crushing chamber 9 so as to be able to rotate on itself around an axis A (Figure 3).

The rotor 11 in turn comprises a central shaft or trunk 13 and a plurality of hammers 15 which protrude radially from the central trunk 13 and are designed to crush the plasterboard panels treated in the plant.

[9] The hammers 15 have a substantially parallelepiped shape or an oblong and relatively thick blade or plate (Figures 2, 3).

Preferably, as shown in Figures 2, 3, each hammer 15 extends parallel, or in any case longitudinally, to the axis of rotation A of the rotor, preferably for most of the average or maximum width of the crushing chamber 9, more preferably at least for three quarters of the average or maximum width of the crushing chamber 9 and, even more preferably, four fifths of the average or maximum width of the crushing chamber 9, where these latter widths are measured parallel to the rotation axis A of the rotor 11.

[10] As shown in Figures 2, 3 each hammer 15 can be fixed to several fixing flanges 14, each of which is approximately in the shape of an equilateral triangle with very rounded or in any case blunt vertices.

Preferably the hammers 15 are fixed to the relative fixing flange 14, or in any case to the rest of the rotor 11, in a substantially rigid way or in any case in such a way as to remain integral and substantially without rotating or translating with respect to the rest of the rotor 11.

As shown in Figure 2, advantageously the outermost longitudinal edge 150 of each hammer 15 is substantially rounded.

[11] Preferably, the rounded outer edge 150 of the hammers 15 has substantially semicircular cross sections (Figure 2). Alternatively, the outer edge of the hammers 15 can have considerably rounded cross sections, for example with minimum radii of curvature R1 equal to or greater than 5 mm, more preferably equal to or greater than 10 mm, and even more preferably equal to or greater than 15 mm.

More generally, as in the embodiment of Figure 7, preferably the outer edge 150â € ™ of the hammers 15 is inclined so as to form, with the closest walls of the crushing chamber 9, a space whose radial height HR is progressively reduces in the opposite tangential direction (arrow F1) to the direction of rotation of the rotor 11 (arrow F2).

[12] Advantageously, the crushing chamber 9 is at least partially delimited by walls 20 covered by projections 18, also indicated, in the present description, "rebound projections 18" (Figure 2). The rebound projections 18 can be for example straight projections or ribs which extend parallel or in any case longitudinally to the rotation axis A of the rotor. The purpose of the rebound projections 18 is to increase the inclination, with respect to the internal walls 20, of the trajectories along which the fragments of the panels to be treated move away from the internal walls after having hit them. In other words, the rebound projections mean that, other things being equal, a plaster fragment that has hit the walls 20 of the chamber tends to rebound more towards a central area of the crushing chamber 9 and towards the rotor 11, instead of ̈ crawl along the walls of the chamber 20 or follow a tangential trajectory to these walls, increasing the number of shocks in the unit of time and the mechanical power that the rotor 11 is able to transfer to the panels to be crushed in the form of energy from bump. For this purpose, each rebound projection 18 is preferably made of metals or in any case materials with a high manganese content. Again for this purpose, preferably each rebound protrusion 18, each rebound protrusion 18 has cross sections of substantially frusto-conical shape, or with the free top rounded or in any case tapered towards the center of the crushing chamber 9.

[13] Preferably the rotor and the internal walls of the crushing chamber are separated by an empty space having a minimum thickness DMIN, in the radial direction, varying between 3-10 mm or between a hundredth and a thirtieth of the maximum diameter of the rotor 11, where this last expression means the diameter of the smallest cylinder which completely inscribes the rotor 11 (Figure 2). More preferably, the minimum thickness DMIN is approximately 5 mm or one sixtieth of the maximum diameter of the rotor 11.

This value of the minimum thickness DMIN helps to avoid excessive tearing and shredding of the paper or cardboard sheets of the plasterboard, thus allowing a more effective separation of the plaster from the paper by sieving.

[14] During the crushing of the panels, the rotor 11 rotates at a speed preferably between 300 and 1500 revolutions per minute, and more preferably between 470 and 1000 revolutions per minute. These speeds of rotation, combined with the particular shape of the rotor 11, of the hammers 15 and of the walls of the crushing chamber 9, are particularly effective in crumbling the plaster of the panels, separating it completely from the paper, cardboard or other sheet material that composes them. , without tearing and shredding excessively - as will be described later - the paper or cardboard.

[15] Unlike, for example, the known plants which, being equipped with toothed drums or multiple augers, finely shred the plasterboard panels and in particular their layer of paper or cardboard, the hammer mill 7 succeeds on the one hand in reducing the drywall in relatively small granules, for example of dimensions mainly not exceeding 10-20 mm, on the other hand it is able to reduce the paper or cardboard layer of the panels into sufficiently large pieces, for example of dimensions not less than 20 mm. This allows to almost completely and very efficiently separate the paper from the gypsum, making sure that the latter is very pure and has an extremely low residual paper content, approximately in the order of 0.08-2%, while the fragments of paper, cardboard or in general cellulosic derivatives resulting from the separation can even have only 1% of residual gypsum.

[16] Advantageously, the hammer mill 7, or other crushing system, is fed by a loading system in turn comprising:

-a hopper 5 designed to receive plasterboard panels or similar building materials from above;

- a compactor 21 designed to crush and compact the plasterboard panels or similar building materials introduced into the hopper;

- an auxiliary feeder 17 designed to push the plasterboard panels or similar building materials introduced into the hopper 5 towards the compactor.

[17] As shown in Figure 4, the compactor 21 is preferably housed inside the hopper 5, and preferably above the auxiliary feeder 17 and downstream of the outlet of the feeder 17 itself, that is of the opening from which the feeder 17 expels the fragments of plasterboard panels or other material to be treated. As shown in Figure 4, the auxiliary power supply is preferably provided with a piston designed to push the plasterboard panels, or other material to be treated, towards the entrance of the compactor 21.

[18] As shown in Figure 4, the piston feeder 17 is preferably arranged below the hopper 5. Preferably the piston is slightly inclined with respect to the horizontal in order to push the crushed material slightly from the bottom towards the € ™ top and introduce it in the upper part of the hammer mill 7.

Preferably, the compactor 21 comprises a rotating wall (Arrow F1 in Figure 4), or another presser, arranged to press against and crush the plasterboard panels or similar building materials introduced into the hopper so as to compact it before it is sent towards the mill. hammers.

[19] Preferably, below or in any case downstream of the hammer mill 7, or other crushing system, there is a screening system (not shown) designed to separate the mass of plasterboard coming from the hammer mill 7 into a fraction enriched in cellulose and a fraction enriched in gypsum.

In the fraction enriched in gypsum, the content by weight of gypsum per unit of mass is substantially greater than the content by weight of gypsum in the plasterboard panels or other material introduced upstream into the plant 1 itself. In the fraction enriched in cellulose, the content by weight of fibrous materials such as paper, cardboard, cellulose or wood derivatives per unit of mass is substantially greater than the content by weight of fibrous materials in the plasterboard panels or other material introduced upstream in the € ™ plant 1 itself.

[20] The screening system can comprise for example one or more screening grids (not shown), preferably vibrating during operation and preferably lying in substantially horizontal planes or in any case with negligible inclination. If the screening grids are more than one, they are preferably superimposed on each other.

All or part of the screening grids preferably have square or rectangular meshes, with dimensions preferably between 2 and 6 cm, and more preferably about 5 X 5 cm.

The screening grids can have dimensions of for example 2 X 1 meter or more preferably larger, for example of 1.5 X 4.5 meters: the larger dimensions of the screening surface better separate the gypsum powder from the oversized cardboard, increasing the yield overall system.

[21] A possible example of system operation 1 is now described.

The sheets, whole or broken, of plasterboard to be treated and also having a maximum width or length of one or more meters are advantageously taken - from a pile on the ground or from a box - by means of a crane equipped with spider or polyp gripper, not shown and of a type known per se. A spider, octopus or another large mechanical gripper, unlike a bucket or mechanical shovel, has the advantage of carrying out a first, rough crushing of the slabs to be treated, reducing the size of the material introduced into the hopper 5, especially when the slabs when grabbed, they are approximately 1-2 meters in size.

[22] In the hopper 5 the plasterboard fragments are compacted both by gravity and because they are crushed downwards by the rotating wall or other presser of the compactor 21, after which they reach the chamber of the piston feeder 17 by gravity. fully back position, the feeder piston pushes the drywall fragments towards the hammer mill 7. Both the piston feeder 17 and the compactor 21 crush and further compact the plasterboard, improving the efficiency of the hammer mill .

[23] The hammer mill 7 further crushes the plasterboard panels, separating the gypsum from the paper or cardboard of the sheets and reducing it to a mass of granules up to 1 cm thick. It can be assumed that the hammer mill described above shatters the panels to be treated mainly through the following mechanisms:

- crumbling caused by the compression of the plaster between the external edges and rounded 150 or inclined 150â € ™ of the hammers 15;

- collisions of the panels against the hammers 15;

- collisions of the panels against the internal walls of the crushing chamber 9;

- collisions of the panels against fragments of other panels to be treated.

[24] In other words, in the crushing chamber the gypsum of the slabs is largely consumed by a myriad of hits against relatively squat bodies, that is, gypsum granules, the hammers 15 or the rebound projections 18; therefore such bumps tear relatively little the sheets of paper or cardboard of the plasterboard plates to be recycled.

Another fraction of the plaster is crumbled by radial compression, after being wedged between the external and rounded edges 150 or inclined 150â € ™ of the hammers 15 and the internal wall 20 of the crushing chamber 9. This crumbling by compression, very effective for shredding the plaster tears and shreds relatively little the paper or cardboard layers of the plasterboard panels.

[25] At the same time the hammer mill 7 still tears - even if, as we have just said, in a limited way - the layers of paper, cardboard or other cellulose-based layers of the plasterboard sheets, reducing them to shreds of size on average large, and variable for example from 2 cm to 0.2 meters. The material thus shredded or shredded falls from the hammer mill 7 onto one or more screening grids, which separate a fraction enriched in coarse cellulose - for example formed by shreds of paper or cardboard larger than 50 X 50 mm , i.e. larger than the mesh size of the grids, and indicatively contaminated by no more than 1% of gypsum dust:

- a fraction enriched in fine cellulose, for example formed by shreds of paper or cardboard with dimensions of less than 50 X 50 mm, i.e. smaller than the mesh size of the grids, and indicatively contaminated by no more than 1% of plaster; And

- a fraction enriched in gypsum, for example formed by granules of dimensions from 0 to 10 mm which in turn are composed of 98-99% of gypsum and about 1-2% of non-separated remains of paper or cardboard;

- small metal fragments, including for example screws or small brackets.

[26] The fraction enriched in coarse cellulose constitutes the so-called oversize fraction, and is removed for example by means of a first conveyor belt, or other continuous oversize conveyor.

The fraction enriched in fine cellulose, the fraction enriched in gypsum and the aforesaid metal fragments, which constitute the so-called underscreen fraction, are removed together for example by means of a second conveyor belt, or other continuous conveyor.

The metal fragments can then be separated by a suitable separator device, for example a magnetic separator known per se, and expelled from the recycling plant 1 through the conveyor belt 29, for example by heaping it on the use yard as shown in Figures 1 , 5; the reference M indicates the pile of metal waste produced by the plant 1.

[27] Reference 31 indicates the conveyor belt with which the fractions enriched in coarse cellulose can be expelled from the recycling plant.

Reference 33 indicates the conveyor belt with which it is possible to expel the fraction enriched in gypsum and fine cellulose from the recycling plant 1, for example by heaping it on the use area as shown in Figure 1; Reference G indicates the pile of granules of the fraction enriched in gypsum produced by implant 1.

[28] Advantageously, the gypsum evacuation conveyor belt 31 is constructed in such a way that it can be easily and quickly disassembled and folded when the plant 1 has to be transported from one place of use to another. For this purpose, as shown in Figures 1, 6, the gypsum evacuation conveyor belt 31 advantageously comprises a frame, for example reticular and substantially rigid, in turn comprising two segments 331, 333 hinged together so that they can be reversibly folded, simplifying moving or transporting the system 1.

[29] Thanks to the previous teachings it is possible to build recycling plants 1 of particularly small size. More specifically, it is possible to make hammer mills 7 of particularly small size and high efficiency, such that they can be mounted on self-propelled systems or in any case easily transportable from one place of use to another. For example, the previously described plant 1, having a total empty weight of about 20 tons, was able to reach a variable productivity between 40-120 tons of plasterboard panels treated per hour. Being able to be moved more easily to different sites of use, even several hundreds or thousands of kilometers away, the plant can be exploited much more intensely and regularly, considerably increasing its operating hours and average annual productivity, and significantly reducing its amortization times. The greater ease of movement also facilitates returns to the manufacturer or retailer and extraordinary repairs and maintenance operations there.

[30] The embodiments described above are susceptible to various modifications and variations without departing from the scope of the present invention. For example, the cross sections of the external edges of the hammers can also be quadrangular or in any case with sharp edges. The rounded surfaces or surfaces with a large radius of curvature of the external edges of the hammers can also be made as suitably faceted surfaces. The various conveyor belts of the recycling plant 1 can be replaced by other types of continuous conveyors, for example slat conveyors.

[31] As an alternative to the motorized wheels or tracks 3 previously described, a recycling plant 1 according to the invention can be made self-propelled more generally by means of a locomotion system fixed to the carcass or load-bearing frame and arranged to allow the moving of the The system itself, and this locomotion system may include not only wheels or tracks, but also for example skates, feet or mechanical legs fixed to the carcass or load-bearing frame. The mechanical feet or legs can be operated by a suitable motor, also mounted on the frame or load-bearing frame of the system 1, allowing the latter to move autonomously. The engine of the locomotion system can be for example internal combustion, electric, pneumatic or hydraulic. The loading system can also be equipped with the hopper 5, and include for example only the compactor 21 and / or the auxiliary feeder 17. Furthermore, all the details can be replaced by technically equivalent elements. For example, the materials used, as well as the dimensions, may be any according to the technical requirements. The examples and lists of possible variants of this application are intended as non-exhaustive lists.

Claims (14)

CLAIMS 1) Plant (1) for recycling plasterboard panels or similar building materials, comprising a hammer mill (7) designed to crush the panels to be treated in the plant, where the hammer mill (7) in turn includes: - a crushing chamber (9); - a rotor (11) mounted inside the crushing chamber (9) so that it can rotate on itself; where the rotor (11) comprises: - a tree or central trunk; And -a plurality of hammers (15) which protrude radially from the central trunk and are designed to crush the panels to be treated in the plant (1). 2) Plant (1) according to claim 1, where at least part of the hammers (15) substantially has the shape of a blade or plate which protrudes radially and extends longitudinally to the rotation axis of the rotor (A) for at least half of the width average or maximum of the crushing chamber. 3) Implant (1) according to claim 1, where at least part of the hammers (15) forms an outer edge (150, 150â € ™) which is radially more outside than the other parts of the hammer itself, extends parallel or longitudinally to the rotation axis (A) of the rotor (11) and has cross sections whose shape is chosen from the following: - domed or semicircle; - beveled or rounded, with minimum radii of curvature (R1) equal to or greater than 5 mm. 4) Implant (1) according to claim 1, where at least part of the hammers (15) forms an outer edge (150, 150â € ™) which is radially more outside than the other parts of the hammer itself, extends parallel or longitudinally to the rotation axis (A) of the rotor (11) and forms a surface that faces the walls of the crushing chamber (9) and is inclined so as to form a space with them, the height of which (HR ) in the radial direction is reduced in a tangential direction contrary to the normal direction of rotation of the rotor (11), so as to crumble by compression the material of the panels to be treated which penetrates into this space. 5) Plant (1) according to claim 1, where at least part of the internal walls of the crushing chamber (9) is covered by a plurality of rebound projections (18) designed to increase the inclination, with respect to the internal walls, of the trajectories along which the fragments of the panels to be treated move away from the internal walls after having hit them. 6) Plant according to claim 5, wherein each rebound projection (18) is substantially oblong and extends parallel or longitudinally to the rotation axis (A) of the rotor (11). 7) Plant (1) according to claim 1, where between the rotor (11) and the internal walls of the crushing chamber (9) there is a minimum distance (DMIN) variable between 3-10 mm and / or between one hundredth and one sixtieth of the maximum rotor diameter. 8) Plant (1) according to claim 1, comprising a loading system arranged to feed the hammer mill (7) and in turn comprising: -a hopper (5) designed to receive plasterboard panels or similar building materials from above; - a compactor (21) designed to crush and compact the plasterboard panels or similar building materials introduced into the hopper (5); - an auxiliary power supply (17) designed to push the plasterboard panels or similar building materials introduced into the hopper (5) towards the compactor. 9) Plant (1) according to claim 8, wherein the auxiliary feeder (17) comprises a piston designed to push the plasterboard panels or similar building materials introduced into the hopper (5) towards the compactor (21). 10) Plant (1) according to claim 8, where the compactor (21) comprises a rotating wall or other presser designed to press against and crush the plasterboard panels or similar building materials introduced into the hopper (5) so as to compact it first that it is sent towards the hammer mill (7). 11) Plant (1) according to claim 1, comprising a screening system arranged to treat the semi-finished material coming from the hammer mill by sieving from it, or in any case separating from it: - a first fraction enriched in gypsum, whose gypsum content by weight per mass unit is substantially greater than the gypsum content by weight in the plasterboard panels or other material introduced upstream into the plant (1) itself; And - a second fraction enriched in cellulose, whose content by weight of fibrous materials such as paper, cardboard, cellulose or wood derivatives per unit of mass is substantially greater than the content by weight of fibrous materials in the plasterboard panels or other material introduced upstream in the plant (1) itself. 12) Plant (1) according to claim 1, provided with: - a casing or load-bearing frame on which the hammer mill (7), any loading system and any one or more screens are mounted; and -a locomotion system fixed to the carcass or load-bearing frame and designed to allow the movement of the system itself, where the locomotion system can include for example wheels, skates, feet, legs and / or tracks (3) fixed to the carcass or bearing frame. 13) Plant (1) according to claim 12, where the locomotion system comprises a motor (35) arranged to drive the wheels, skates, feet, legs and / or tracks (3) fixed to the casing or load-bearing frame allowing the plant (1) to move autonomously, that is without being towed or pushed by vehicles or motor vehicles external to it. 14) Process for recycling plasterboard panels or similar building materials, comprising the operation of crushing the plasterboard panels or similar building materials by means of a hammer mill (7) having the characteristics according to claim 1.