WO2019206575A1

WO2019206575A1 - Impact mill with launcher

Info

Publication number: WO2019206575A1
Application number: PCT/EP2019/058169
Authority: WO
Inventors: Eric GHIDINELLI
Original assignee: ZATO Srl
Current assignee: ZATO Srl
Priority date: 2018-04-23
Filing date: 2019-04-01
Publication date: 2019-10-31
Anticipated expiration: 2020-10-23
Also published as: IT201800004775A1

Abstract

An impact mill, comprising a loading region (4) which is connected to an underlying launch region (3) provided with at least one secondary rotor (31a, 31b) which has a horizontal rotation axis (H2, H3), the at least one secondary rotor comprising respective secondary hammers (32a, 32b) which are extended radially on the peripheral region of the respective secondary rotor in order to affect a flow of loose material that arrives from the loading region and propel it toward an underlying impact breakup region (2), the impact breakup region comprising a main rotor (21) having a horizontal rotation axis (H1) which is enclosed laterally by plating (23) and has a plurality of main hammers (22) which extend radially on the peripheral region of the main rotor in order to affect the loose material propelled from the launch region (3), the rotation of the at least one secondary rotor (31a, 31b) being concordant and in step with the rotation of the main rotor (21) so that the loose material propelled by one of said secondary hammers (32a, 32b) strikes directly after launch a face of one of the main hammers (22), characterized in that the rotation axes of the main rotor (H1) and of the at least one secondary rotor (H2, H3) lie on a geometric plane (P2) which is inclined with respect to a vertical plane (V1).

Description

IMPACT MILL WITH LAUNCHER

The present invention relates to an impact mill with launcher.

In order to break up loose material such as broken stone and rubble, in the mining industry sector it is known to use so-called impact mills for the further reduction of the loose material obtained in a quarry from crushers, which typically has a maximum size on the order of 100 mm for so-called secondary mills and on the order of 30 mm for so-called tertiary mills.

These impacts mills typically have the problem of reconciling the high peripheral speed of the hammers, which is required for breakup by impact, with the need to make the material pass so that it is struck by the face of the hammer.

Impact mills are known which, upstream of a breakup rotor with a horizontal rotation axis, comprise a second rotor having a smaller diameter, also known as launcher, which receives from above the loose material and is also able to rotate on a horizontal rotation axis that is aligned with the rotation axis of the breakup rotor along a same vertical line. This launcher is able to rotate concordantly with and at the same speed as the breakup rotor, with an appropriate phase difference. By means of the rotation of the second rotor, the loose material follows a circular path and is launched against the hammers of the breakup rotor along an inclined direction, so as to add the speed of the loose material to the speed of the hammer.

One drawback of the known solution described above is that the vertical alignment of the two rotors forces the loose material in input to fall on the rotation axis of the second rotor and therefore to be possibly affected by the hammers of the secondary rotor in a region having a smaller radius.

Furthermore, this arrangement requires the cylindrical walls around the rotor to be beveled at the material inlet hopper, so as to reduce the possibility that at this point the material jams between a hammer of the secondary rotor and one of these cylindrical walls. The aim of the present invention is to provide an impact mill with launcher that is capable of improving the background art in one or more of the aspects indicated above.

Within this aim, an object of the invention is to provide an impact mill that facilitates the penetration of the loose material in the impact mill.

Another object of the invention is to provide an impact mill that is subjected to reduced wear of its internal plating.

Another object of the invention is to provide an impact mill with launcher that is highly reliable, relatively easy to provide and at competitive costs.

This aim, as well as these and other objects which will become better apparent hereinafter, are achieved by an impact mill according to claim 1, optionally provided with one or more of the characteristics of the dependent claims.

Further characteristics and advantages of the invention will become better apparent from the description of a preferred but not exclusive embodiment of the impact mill according to the invention, illustrated by way of nonlimiting example in the accompanying drawings, wherein:

Figure 1 is a sectional view, taken along a vertical plane, of an impact mill according to the invention in a first configuration for use;

Figure 2 is a view of the impact mill of the preceding figure in a second configuration for use;

Figure 3 is an enlarged- scale view of the chamber of one of the launchers according to the invention.

In the following description, the expression "vertical" will be used to define a direction that is oriented like the force of gravity or substantially perpendicular to the resting surface of the footing of the impact mill, while the expression "horizontal" will reference a direction that is perpendicular to the vertical one.

With reference to the cited figures, the impact mill according to the invention, designated generally by the reference numeral 1, is of the type with a horizontal axis and comprises an impact breakup region 2, a launch region 3 and a region 4 for loading the loose material, for example an inert material such as broken stone or rubble.

The impact breakup region 2 is per se of a known type and comprises a substantially cylindrical chamber which has a hammer mill 20 and plating 23 arranged along the walls of the chamber. The hammer mill 20 comprises a main rotor 21, which can rotate with respect to a first horizontal axis HI and on which multiple hammers 22 are fixed and are distributed angularly regularly along the peripheral region of the main rotor 21. In the illustrated case, the hammers 22 are two and are therefore fixed at a mutual angular distance of 180°, i.e., in diametrically opposite positions of the main rotor 21. Preferably, the hammers 22 have a tapered shape which widens away from the first rotation axis HI, so as to define planar surfaces that are inclined with respect to the radial direction.

The hammer mill 20 is of the reversible type, i.e., it is actuated rotationally by a motor so as to rotate clockwise or counterclockwise on the basis of a command set by a user.

The launch region 3 is mounted vertically above the breakup region 2 and vertically below the loading region 4 of the loose material.

The launch region 3 comprises at least one secondary rotor 31a provided with a plurality of secondary hammers 32a which are angularly distributed regularly along the peripheral region of the secondary rotor 31a. In the illustrated case, the secondary hammers 32a are two and are therefore fixed at a mutual angular distance of 180°, i.e., in diametrically opposite positions of the secondary rotor 31a.

The secondary rotor 31a has a smaller diameter than the main rotor 21. The ratio of the two diameters depends on the size of the loose material to be broken up and can be the one notoriously used in the field. For example, the ratio can be from 4 to 7 for maximum sizes of the input material of approximately 30 mm, or can be less than 4 but greater than 1 for larger sizes.

The secondary rotor 31a can rotate about a second horizontal axis H2 which is parallel to the first rotation axis HI and forms with the latter a geometric plane P2 which is inclined with respect to a vertical plane VI, i.e., forms with the vertical plane VI an angle that is greater than 0°.

The secondary rotor 31a is enclosed in a chamber 33a which communicates in a lower region with the breakup region 2 and in an upper region with the loading region 4 and is delimited laterally by an external wall 34a and by an internal wall 38a, which are mounted on the casing of the impact mill 1 so as to define an inlet 30a, for the loose material that arrives from the loading region 4, and an outlet 39a, for the loose material launched towards the hammers 22 of the main rotor 21.

The central vertical axis V2 of the inlet 30a is preferably spaced laterally from the vertical geometric plane on which the rotation axis H2 of the secondary rotor 31a lies, so that the loose material does not fall directly onto the central part of the secondary rotor 31a, but at its peripheral region, and in particular at the descent trajectory followed by the secondary hammers 32a.

The external wall 34a is extended along the horizontal direction (i.e., parallel to the rotation axis H2), maintaining a transverse cross-section that is preferably substantially J-shaped, i.e., with a vertical flat portion 35a, a cylindrical portion 36a and an inclined flat portion 37a, all mutually radiused without surface discontinuities.

The vertical flat portion 35a is substantially radiused with a vertical lateral surface 43a of the loading region 4 and is adapted to guide the falling loose material toward the cylindrical portion 36a.

The cylindrical portion 36a of the external wall 34a is substantially a surface of a cylindrical sector that has a radius that is substantially equal to the radius of the secondary rotor 31a, so as to not allow the loose material to jam between the secondary hammers 32a and the external wall 34a. For the same reason, the internal wall 38a also has a cylindrical portion in a position that is diametrically opposite with respect to the cylindrical portion 36a and has a radius of curvature that is substantially equal to the radius of the secondary rotor 31a.

The inclined portion 37a of the external wall 34a forms a sort of ramp for launching the loose material against the hammers 22 of the main rotor 21 and is inclined essentially along the tangential launching trajectory of the loose material.

Preferably, the impact mill 1 according to the invention is provided with a pair of secondary rotors 31a and 31b that have a horizontal rotation axis and are used alternately with respect to each other, i.e., it also comprises a second secondary rotor 31b, which is preferably identical to the first secondary rotor 31a that has already been described and which, in the second configuration for use of the impact mill 1 (Figure 2), is made to rotate in the opposite direction with respect to the direction of rotation of the first secondary rotor 31a in the first configuration for use of the impact mill 1 (Figure 1). Therefore, the secondary rotors 31a and 31b can rotate with mutually discordant directions of rotation during their respective use, i.e., when they propel the loose material in the breakup region 2.

The secondary rotors 31a and 31b are preferably arranged on symmetrically opposite sides with respect to the vertical plane VI that passes through the rotation axis HI of the main rotor 21.

The second secondary rotor 31b is mounted so that it can rotate in the casing of the impact mill 1 laterally adjacent to the first secondary rotor 31a and is preferably identical to the latter, i.e., it has the same diameter and the same number and arrangement of secondary hammers 32b. Its horizontal rotation axis H3 is parallel to the rotation axes HI and H2 and in the illustrated embodiment defines a substantially horizontal geometric plane together with the rotation axis H2 of the first secondary rotor 31a. The second secondary rotor 31b also is enclosed in a chamber 33b which communicates in a lower region with the breakup region 2 and in an upper region with the loading region 4 and is delimited laterally by an external wall 34b and an internal wall 38b. Said walls 34b and 38b are also mounted on the casing of the impact mill 1 so as to form an inlet 30b, for the loose material that arrives from the loading region 4, and an outlet 39b, for the loose material that is propelled toward the hammers 22 of the main rotor 21.

The walls 34b and 38b are shaped mirror- symmetrically with respect to the walls 34a and 38a, relative to the vertical plane VI that passes through the rotation axis HI of the main rotor 21. In this manner, the central vertical axis of the inlet 30b also is spaced laterally from the vertical geometrical plane on which the rotation axis H3 of the second secondary rotor 31b lies, so that the loose material does not fall directly onto the central part of the second secondary rotor 31b but at its peripheral region, and in particular at the descent trajectory followed by the secondary hammers 32b.

The external wall 34b is extended along the horizontal direction, maintaining a transverse cross-section that is preferably shaped substantially like a letter J which is inverted in a mirror- symmetrical manner and therefore has a vertical flat portion 35b, a cylindrical portion 36b and an inclined flat portion 37b which are substantially identical but mirror- symmetrical with respect to the vertical plane VI, to the corresponding portions of the external wall 34a described previously.

The secondary rotors 32a and 32b are used in a mutually alternative manner, i.e., only one of them is used to launch the falling loose material toward the hammers 22 when the impact mill 1 is in operation. The secondary rotors 32a and 32b can be connected kinematically to the main rotor 21 or to the motor of the main rotor 21 so that the secondary rotor used between the two secondary rotors 31a and 31b rotates concordantly with the main rotor 21 and at the same rotation rate as the latter, i.e., with the same number of revolutions per minute.

As mentioned, the breakup mill 20 is of the reversible type and is therefore is actuated by a motor (not shown) which is connected to the main rotor 21 and is configured to rotate in both directions of rotation under the control of the user.

The secondary rotors 3 la-3 lb are preferably mutually connected by means of a toothed transmission, for example a belt, and one of said secondary rotors is connected to a pulley of the main rotor 21 by means of another toothed transmission, for example another belt.

The loading region 4 of the impact mill 1 can be preferably provided as in Figures 1 and 2, i.e., with a hopper 41 at one inlet 42 and two outlets 43a-43b which can be selected alternately by means of an oscillating baffle 44 and are mounted above the respective inlets 30a-30b of the launchers.

As an alternative to the oscillating baffle 44, it is possible to use as a means for diverting the falling loose material a carriage that can slide horizontally and on which the hopper is mounted, in order to selectively connect the hopper to one or the other of the inlets 30a or 30b.

By using two secondary rotors arranged side by side like the ones described, it is possible to reduce the overall wear of the plating 23 of the mill 1. The loose material broken up by the impact is in fact prevented from being always propelled onto the same internal wall of the breakup region 2 by means of a reversal of the direction of rotation of the main rotor 21 and the use of the launcher, in which the secondary rotor 31a or 31b rotates concordantly with the current direction of rotation of the main rotor 21. In particular, the reversal of the main rotor 21 can occur by means of the movement of a manual lever connected to the baffle 44 and by starting the motor of the main rotor in the direction of travel that corresponds to the selected position of the baffle 44.

The operation of the impact mill according to the invention is evident from the preceding description. In particular, starting from the first configuration of use shown in Figure 1, the oscillating baffle 44 is oriented so as to block the outlet 43b and the loose material that is made to fall into the hopper 41 is diverted entirely toward the outlet 43a.

The first secondary rotor 31a and the main rotor 21 rotate at the same rotation rate and clockwise.

The loose material thus falls vertically into the chamber 33a of the first secondary rotor 31a and laterally with respect to the rotation axis H2, so that the secondary hammers 32a push it along an essentially circular trajectory. When it arrives at the free end of the inclined wall 37a, the loose material is consequently propelled toward a hammer 22 of the breakup mill 20 along a direction that is substantially tangent to the circumference traced by the center of gravity of the secondary hammers 32a.

As a consequence of the impact, the broken up material is propelled against the beams of the plating 23 of one side of the mill 1.

In order to reduce the wear of said beams, when the motor is off the user moves the baffle 44 so as to block the outlet 43a and open the outlet 43b, reverses the direction of rotation of the motor of the main rotor 21 and, after starting, the second secondary rotor 31b rotates concordantly with the reversed direction of rotation of the main rotor 21, i.e., counterclockwise as shown in Figure 2. The broken up material is thus propelled towards the beams of the plating on the other side of the impact mill 1.

In practice it has been found that the invention achieves the intended aim and objects.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims; all the details may furthermore be replaced with other technically equivalent elements.

In practice, the materials used, so long as they are compatible with the specific use, as well as the contingent shapes and dimensions, may be any according to the requirements and the state of the art.

The disclosures in Italian Patent Application No. 102018000004775 from which this application claims priority are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

1. An impact mill, comprising a loading region (4) which is connected to an underlying launch region (3) provided with at least one secondary rotor (31a, 31b) which has a horizontal rotation axis (H2, H3), said at least one secondary rotor comprising respective secondary hammers (32a, 32b) which are extended radially on the peripheral region of the respective secondary rotor in order to affect a flow of loose material that arrives from said loading region (4) and propel it toward an underlying impact breakup region (2), said impact breakup region comprising a main rotor (21) having a horizontal rotation axis (HI) which is enclosed laterally by plating (23) and has a plurality of main hammers (22) which extend radially on the peripheral region of the main rotor (21) in order to affect the loose material propelled from said launch region (3), the rotation of said at least one secondary rotor (31a, 31b) being concordant and in step with the rotation of said main rotor (21) so that the loose material propelled by one of said secondary hammers (32a, 32b) strikes directly after launch a face of one of said main hammers (22), characterized in that said rotation axes of the main rotor (HI) and of said at least one secondary rotor (H2, H3) lie on a geometric plane (P2) which is inclined with respect to a vertical plane (VI).

2. The mill according to claim 1, wherein said launch region comprises at least one inlet of the loose material (30a, 30b) which has a vertical central axis (V2) that is spaced laterally with respect to the respective rotation axis (H2, H3) of said at least one secondary rotor (31a, 31b).

3. The mill according to one or more of the preceding claims, wherein said at least one secondary rotor (31a, 31b) of the launch region (3) is formed by a first secondary rotor (31a) and by a second secondary rotor (31b) which are arranged mutually side by side and can rotate with mutually discordant rotation directions during respective use, each secondary rotor comprising respective secondary hammers (32a, 32b).

4. The mill according to claim 3, wherein said main rotor (21) is reversible and can be connected alternately to said first secondary rotor (31a) or to said second secondary rotor (31b) so as to rotate concordantly with the secondary rotor connected thereto and at the same rotation rate.

5. The mill according to claim 3, wherein said main rotor (21) is reversible and is connected to at least one between said first and second secondary rotors by means of a first transmission, said secondary rotors being mutually connected by means of a second transmission.

6. The mill according to one or more of the preceding claims, wherein said loading region (4) comprises a hopper (41) and redirection means (44) for directing the material that falls into the hopper selectively toward said first secondary rotor (31a) or toward said second secondary rotor (31b).

7. The mill according to one or more of the preceding claims, wherein said at least one secondary rotor (31a, 31b) is enclosed in a chamber which is connected in a lower region to the breakup region (2) and in an upper region to the loading region (4) and is delimited laterally by an external wall (34a, 34b) and an internal wall (38a, 38b), said external wall (34a, 34b) being extended along the horizontal direction (H2, H3), maintaining a transverse cross-section that is substantially J-shaped.

8. The mill according to claim 7, wherein said external wall (34a,

34b) comprises a vertical flat portion (35a, 35b), a substantially cylindrical portion (36a, 36b) and preferably an inclined flat portion (37a, 37b).

9. The mill according to claim 8, wherein the vertical flat portion (35a, 35b) is substantially blended with a vertical lateral surface (43a, 43b) of the loading region (4) and is adapted to guide the falling loose material toward the substantially cylindrical portion (36a, 36b).