WO2003099470A1

WO2003099470A1 - Vibrating screen for rubble treating plants

Info

Publication number: WO2003099470A1
Application number: PCT/EP2003/005454
Authority: WO
Inventors: Angelo Toschi
Original assignee: Pescale S.P.A.
Priority date: 2002-05-24
Filing date: 2003-05-26
Publication date: 2003-12-04
Also published as: ITMI20021137A1; ITMI20021137A0

Abstract

A sorting vibrating screen for rubble treating plants comprising a screen frame (2), a screening grating-like surface (6) having invariable openings (7), and a longitudinally following screening surface (8) having variable openings (9), wherein a) the screening surface (6) having invariable openings (7) covers the substantially part of the total screen surface, b) the screening surface (8) having variable openings (9,; 27) is formed by a single transverse row of variable, that is elastically opening openings (9; 27), and c) said variable openings have either an abutment slot (21, openings 9) which substantially extends in the longitudinal screen direction, or said variable openings (27) define a first invariable opening (28) directly facing the end (12) of the screen surface (6) having invariable openings (7) and two following lateral substantially longitudinal cuts (29) defining a flexible blade (25) which opens transversally to the longitudinal screen direction. By equal screen dimensions the screening power and the plant productivity are increased.

Description

VIBRATING SCREEN FOR RUBBLE TREATING PLANTS

Background of the invention The present invention relates to a sorting vibrating screen for rubble treating plants according to the preamble of claim 1. The invention also relates to a plant including such a sorting vibrating screen.

As is known, building rubble are made of different components, like tiles, concrete, cement, reinforcing rods, metal and wooden doors and windows, broken glass plates, water-closets, wash basins, mason buckets, paint barrels, working shoes, stones, pebble gravel, sand, cement powder, and so on, the granulometry of which when entering the crushing mill varies from values laying a bit above 0, for example from 0,1mm up to 120 mm for the crushable rubble, whereas the flexible and foldable materials, like iron rods, plastic pieces, pieces of metal window and door frames, pieces of cement sacks, pieces of paving tiles boxes, and so on keep considerable dimensions having irregular shapes and form a so called oversized fraction, also defined as "macro" fraction.

The known rubble treating plants are usually provided with several stages of separating or sorting screens for different granulometries, which stages are formed by several types of known screen constructions.

A screen allowing a sorting of two fractions having two different granulometries is disclosed in the patent EP 0 784 508 Bl of the applicant, which has a substantially rectangular shape of, for example, 1.500 mm x 4.000 mm and in which substantially a first half screen surface is provided with screening invariable openings, whereas the second screen half surface is provided with variable openings which are formed by elastic blades which opens under the weight of the heavier rubble pieces and, after the throughgoing of the latter, elastically jump back and close said elastically variable openings. Said elastic blades are obtained by means of cuts or notches in a respective plate or panel made of rubber or the like. With a such screen used as a first stage for sorting building rubble leaving a crushing mill with a granulometry of, for example 0,1 - 120 mm, the rubble flow is first sorted through said invariable screening openings in a fraction smaller than 30 mm, whereas through said variable screening openings is sorted a fraction having a granulometry in the range of 30-70 mm, and the remaining yet bigger fraction of 70-120 mm is discharged and re-conducted to the crushing mill, wherein the macro fraction after having been conducted along the entire screen length is discharged in a collecting zone or container.

The transport of the various fractions between the single sorting stages, the crushing mill and the discharging zones of the different fractions is carried out by means of motorized conveying belts With the screen disclosed in the EP 0784 508 Bl may be practically achieved the advantages mentioned therein. However, it has been noted that with such screens it is not possible to increase as desirable the screening power and the productivity of a plant comprising these sorting screens while maintaining an optimized sorting quality and without disturbing the balances of a correct sorting in the other plant screening screens or stages.

Summary of the invention

Accordingly, the aim of the present invention is to provide a sorting screen or stage for rubble treating plants able to substantially increase his screening power and sorting efficiency as well as to substantially increase the plant productivity.

The above mentioned aim is achieved by a sorting screen or stage having the features of claim 1.

Further advantageous improvements and embodiments are disclosed in the dependent claims.

With a sorting screen according to the invention and a rubber treating plant including such sorting screen it is possible to achieve several important advantages. The fact of having considerably increased the traditional screening surface, that is the screening surface provided with invariable openings, and to have designed only one row of variable openings with either a longitudinal clearance like a double-leafed door in the longitudinal screen direction or a transversal acting variable opening following an invariable opening directly facing the end of the screen surface having invariable openings, allows, with screens having the same size, to drastically increase the screening power and efficiency and to also ensure a quick and reliable discharge of the macro fraction. It has been noted indeed that a greater transit speed of the crushed rubble flow allows a quick transition of the macro fraction on the entire screen so that the combined action of a greater speed of the rubble flow and the greater mobility of the heavier rubble components or fractions drastically reduces that accidentally timely covering action of the openings of the screen according to the EP 0 784 508 Bl which covering action contributed to limit the screening efficiency and, indirectly, the plant productivity. Another advantage is to be seen in the fact that it is possible to achieve a greater screening efficiency and plant productivity without requiring any external energy source. Still another advantage is to be seen in the assembling and maintenance easy and quickness of the screens according to the present invention.

Due to the fact that in an embodiment the elastic blades are formed by simple punched rubber plates having a small size it is possible to substantially reduce the manufacturing costs. The same advantage is also achievable with the rubber blades proposed in another embodiment.

Still another advantage is that the screens according to the present invention are easily interchangeable with existing screens, so that it is possible to increase the productivity of existing plants in a extremely simple and cheap manner. Another advantage of the screens according to the present invention is to be seen in the possibility to adjust the slant of the surface provided with the elastically variable openings with respect to the surface provided with invariable openings, so that the screen can be easily and quickly adjusted in function of the rubble types to be respectively treated, that is in function of the estimated quantity and types of the components of the macro fraction to be expected in the rubble to be treated.

Brief description of the drawings Further characteristics and advantages of a sorting screen for building rubble treating plants according to the invention will become more apparent hereinafter from the following disclosure of three embodiments which are schematically and in different scales illustrated in the accompanying drawings, in which:

Figures 1, 2 and 3 are a top view and cross sections along the sectional planes II-II and III-III of Figure 1 of a screen according to the present invention, respectively;

Figure 4 shows a lateral view of the screen of Figure 1 in the usual installation position;

Figure 5 is a top view of the screen surface provided with variable openings; Figure 6 is a frontal view of the screen of Figures 1 and 5, according to the arrow F;

Figure 7 shows a detail of a second embodiment of the screen of

Figure 1;

Figure 8 is a top view of the screen surface provided with variable openings according to a further embodiment;

Figure 9 shows a cross section along the sectional plane IX-IX of the detail of Figure 8 while falling of a small rubble flow component; and

Figure 10 shows a cross section along the sectional plane IX-IX of the detail of Figure 8 while falling of a greater rubble flow component still within the greater desired granulometry.

Description of the preferred embodiments

Reference is first made to the embodiment of Figures 1 to 6. The screen according to the invention is denoted by 1. In the shown example, the screen has a rectangular frame 2 which is formed, for example, by L-shaped sections 3 and I-shaped sections 4. In a practical example said screen has a length a of 1.500 mm and a total length b of 5.000 mm, a length c of 4.550 mm defining the grating- like part or surface 6 provided with invariable openings 7, as well as a length d of 450 mm of the surface 8 provided with variable openings 9, that is with elastic blades 11 consisting of rubber or rubber-like material.

The arrow FI indicates the feeding direction of the not shown rubble flow to be sorted. According to the present invention after the surface 6 provided with invariable openings 7 follows the surface 8 provided with variable openings 9, for example by welding to the end section 12 having a L-shaped cross section supporting sections 13, 14 and 16 having the shape of arms 12 projecting from the frame 2, Figures 5 and 6. The elastic blades 11 consisting of rubber or rubber-like material are formed by a rectangular sheared plate 17, Figure 6. In order to allow a simple assembling and disassembling said plates 17 in a preferred embodiment are sandwich-like housed between a lower section or arm 16 and an upper removable section or arm 18, wherein the latter has a triangular cross section in order to not disturb the transit of the greater fractions and the macro fraction. Practically the connection between said sections 16 and 18 takes place by means of a number of screws 19 which are screwed in threaded holes provided in said sections 18. Practically said projecting sections 13 and 16 are also connected together at the external end thereof. They could obviously also been substituted with other projecting arms 20 having any form as desired.

According to the present invention each variable opening 9 which is defined between two adjacent arms 20 is covered by two opposite elastic blades 11 which are freely downwards flexible in said opening 9 and have an abutment slot or clearance 21 in the range of 1-2 mm up to 8-10 mm or more, like a double leafed door. In the embodiment shown in Figure 1 four variable openings 9 are provided the width of which is greater than 350 mm. Due to design reasons of the frame 2 both external variable openings 9 have a width of 390 mm whereas both internal variable openings 9 have a width of 360 mm. This is in any case a matter of choice so that said four variable openings 9 could also have the same width. According to the invention the length of said variable openings 9, that is of said elastic blades 11, is provided rather greater than the width of said variable openings 9 in order to ensure a reliable opening time of said rubber blades and therewith a sure fall of heavy rubble pieces having the desired granulometry, that is in the shown example 30-70 mm.

With the proposed conformation of the variable openings 9 in the form of openings with blades 11 disposed like a double-leafed door it is practically possible to simultaneously obtain from a single rubber plate 17 two blades 11 for two adjacent openings 9. Due to obvious geometrical reasons in the shown example each of both external plates 17 forms a single blade 11. As shown in Figure 4, between the surface 6 provided with invariable openings 7 and the surface 8 provided with variable openings 9 is formed an angle α of, for example, 5°. The reason of providing this angle is to ensure an optimized transit of the pieces of the greater fractions and the macro fraction on the surface 8 with variable openings. Due to the fact that the proportions among the various rubble components may vary in accordance with the rubber origin, in an embodiment according to the present invention it is provided to hinge the supporting structure of the surface 8 having variable openings 9 to the frame 2 of the surface 6 having invariable openings 7, as shown in 22 in Figure 5. This can be done with one of the several known manner well known to those skilled in the art.

In the embodiment shown in Figures 8 to 10 the surface 8 provided with variable openings 9 uses the same supporting structure 13, 14, 16 and 18 illustrated for the embodiment of Figures 1 to 6, however the variable openings 9 have another configuration allowing to increase the screening power and efficiency as well as the productivity of a plant including such screen. As inferable from Figure 8 all elastic blades 25 may be obtained in a single rubber plate 26. In more details, each variable opening 27 is formed by an invariable opening 28 directly facing the end section 12 of the screen frame 2 and a following variable opening defined by a blade 25 which is formed by two substantially longitudinal lateral cuts 29.

Good results have been achieved with a length L of said cuts 29 equal to the length LI of the invariable opening portion of the total variable openings 27.

Working

The operation of the screen 1 according to the embodiment of

Figures 1 to 6 placed in a sorting stage of a not shown rubble treating plant is as follows:

The not shown rubble flow conveyed on the screen 1 advances first along the surface 6 having invariable openings 7, wherein during said advancement the rubble parts having the smaller granulometries fall through the invariable openings 7 provided in the grating-like surface 6. The rubble parts having greater granulometries and the macro parts after having moved along the grating-like surface 6 come to the surface 8 having variable openings 9, where the heavier pieces having a greater granulometry, that is between 30 and 70 mm, during the transit thereof on the rubber blade 11 cause the bending of said blades downwards, that is in an opening movement, as shown in Figure 6. Due to the length of the variable openings 7 it is achieved the fact that the fall of the pieces of the fraction of 30-70 mm takes place in a quick and reliable way. On the contrary, the macro parts slide along the screen 1, that is above the rubble flow sliding on the screen 1, on the surfaces 6 and 8 and then fall per gravity on a not shown chute directed to a not shown collecting container or zone for collecting said macro components.

By providing on the one hand a large grating-like surface 6 and on the other hand a following surface 8 having reliable opening elastic blades 11 which reliable open and have a length which is greater than the length of the variable openings of the known screens, however smaller than the total length of the surface having variable openings of the known screens, so that the macro parts quickly slide on said blades 11 conformed like a double-leafed door, it has been possible to achieve an optimized balance between the screening power of both surfaces 6 with invariable openings 7 and 8 with variable openings 9 while eliminating at the same time the various reasons of temporary clogging of the screen openings caused by the macro parts which transit more slowly, as happens on the known screens. The working of the embodiment of Figures 8 to 10 differs from the one of the embodiment of Figures 1 to 6 only by the fact that after the transit on the screen surface 6 provided with the invariable openings 7 the rubble pieces having a granulometry greater than that of the invariable openings 7 of the surface 6 directly fall through the invariable section 28 of the variable openings 27, as shown in Figure 9, whereas the rubble pieces having a still greater granulometry but smaller than the greatest desired granulometry of, for example, 70 mm will push downwards the flexible blades 25 and fall trough the provided variable openings 27, as shown in Figure 10.

The obtained first quick discharging of part of the rubble components through the invariable part 28 of the variable openings 27 results in a great increasing of the screening power and efficiency of this embodiment as well as of the productivity of a rubble treating plant including such a screen.

Although very good results have been achieved by using rubber blades or plates the latter could obviously be replaced by plastics or any suitable elastic material. Also the dimensions, which have been stated as an example, could obviously be changed in accordance with the considered granulometry and/or plant.

In practicing the invention it has been observed that by replacing in an existing plant the panel for the first sorting, that is the panel downstream the stage for the removing of the ferrous components, by a screen according to the embodiment of Figures 1 to 6 it has been possible to increase the screening power and the plant productivity for an amount greater than 100%. By using a screen according the embodiment of Figures 8 to 10 the amount of the screening power and the plant productivity has been further increased in comparison of the results obtained with the embodiment of Figures 1 to 6.

From the above constructional and operating disclosure, it should be apparent that the screens according to the present invention efficiently achieve the indicated aim and the mentioned advantages. In practicing the invention, one skilled in the art can perform modifications or variations, such as, for example, that of providing different support structures both for the grating-like surface having invariable openings as well as for the surface having variable openings, of providing the screen in a single or double form, that is in sorting stages with superimposed screens and so on, without departing from the scope of the invention.

Claims

Claims 1. A sorting vibrating screen for rubble treating plants comprising:

- a screen frame,

- a screening grating-like surface having invariable openings, and - a longitudinally following screening surface having variable openings, characterized in that a) the screening surface (6) having invariable openings (7) covers the substantially part of the total screen surface, b) in that the screening surface (8) having variable openings (9; 27) is formed by a single transverse row of variable, that is elastically opening openings (9; 27), and c) in that said variable openings have either an abutment slot (21, openings 9) which substantially extends in the longitudinal screen direction, or said variable openings (27) define a first invariable opening (28) directly facing the end (12) of the screen surface (6) having invariable openings (7) and two following lateral substantially longitudinal cuts (29) defining a flexible blade (25) which opens transversally to the longitudinal screen direction.

2. Screen according to claim 1, characterized in that said variable openings (9) are defined by two opposite blades (11) which are in abutment with a clearance (21) like a double-leafed door.

3. Screen according to claim 1, characterized in that two adjacent blades (11) of two adjacent variable openings (9) are formed by a single rubber plate (17) which extends for an half in one opening (9) and for the other half in the adjacent variable opening (9).

4. Screen according to claim 1, characterized in that each of said variable openings (27) is defined by a single rubber blade (25) which defines a first invariable opening (28) directly facing the end (12) of the screen surface (6) provided with invariable openings (7) and is provided with two following lateral substantially longitudinal cuts (29) defining the length of said elastic blade (25).

5. Screen according to claim 4, characterized in that all said elastic blades (25) are obtained in a single rubber plate (26).

6. Screen according to one or more of the preceding claims, characterized in that the elastic blades (11, 25), that is the blade plates (17, 26) are sandwich-like removably supported by a number of arm projecting couples (16, 18) formed by a lower supporting arm (16) which is fixed to the screen frame (2) and an upper removable arm (18), wherein the connection between the fixed and the removable arms (16, 18) is carried out by means of a number of screws (19).

7. Screen according to claim 1, characterized in that the screen surface (6) provided with invariable openings (7) and the screen surface (8) provided with variable openings (9; 27) define an angle (α) in the range of 2° and 8°, preferably of 5°.

8. Screen according to claim 1, characterized in that the supporting arms (16, 18) supporting said elastic blades (11, 17; 25, 26) are supported on the screen frame (2) in a swingable manner (22) and can be fixed in different slanting positions.

9. Screen according to claim 1, characterized in that it has a width of about 1.500 mm and a length of about 5.450 mm, wherein the length of the surface (6) provided with invariable openings (7) is of about 5.000 mm whereas the surface (8) provided with variable openings (9) has a length of about 450 mm.

10. Screen according to one or more of the preceding claims, characterized in that four variable openings (9) are provided which have an equal length or both external variable openings (9) have a width of about 390 mm whereas both internal variable openings (9) have a width of about 360 mm, wherein in each variable opening (9) both blades (11) define an abutment slot (21) in the range of 1 or 2 mm up to 15 mm, and preferably of 8 mm.

11. Screen according to one or more of the preceding claims, characterized in that the length (LI) of said invariable opening (28) of the variable openings (27) and the length (L) of the following lateral cuts (29) of each elastic blade (25) are substantially equal.

12. Screen according to one or more of the preceding claims, characterized in that it forms a screening stage having a known box and vibration means.

13. Building rubble treatment plant, characterized in that it comprises a screening stage provided with a screen (1) according to one or more of the preceding claims.