a) Field of the Disclosure
This disclosure relates to rock (material) grinding mills and more particularly to a conjugate anvil-hammer mill (CAHM) having a conjugate rotating outer ring housing and rotating inner ring, where the inner ring and outer ring surface interfaces cooperate, and where the respective inner ring outer diameter surface and outer ring inner diameter surface are synchronized to comminute material fed between the rings.
b) Background Art
For many industrial purposes it is necessary to reduce the size of rather large rocks to a much smaller particle size (commonly called “comminution”). For example, the larger rocks may be blasted out of an area such as a hillside, pit or mine, and these larger rocks (sometimes the size of boulders) are then directed into a large rock crusher, which is typically the first stage of comminution after blasting. The blasted rock sizes can exceed 1000 mm (>40 inches) in size. The resulting output of the crusher is typically smaller rock that is less than 200 mm (8 inches) in a longest dimension which is then fed to a grinding mill. The grinding mill typically comminutes the crushed rock down to 50 mm (>2 inches) sized rocks or less.
One common grinding mill comprises a large cylindrical grinding section, rotating along its horizontal axis, which often could have a diameter of as much as ten to fifty feet. One such mill is described in U.S. Pat. No. 7,497,395 incorporated herein by reference. The material (rocks), along with water or air, are directed into one end of the continuously rotating grinding section, which comprises various types of lifting ribs positioned axially on the inside surface of the grinding section to carry the rocks upwardly, on its surface, in a curved upwardly directed path within the grinding chamber so that these partially ground rocks tumble back onto other rocks in the lower part of the chamber. Thus, these rocks impact each other, and the inner surface of the grinding mill, and are broken up into smaller rock fragments. Also, sometimes large iron balls (e.g., two to six inches in diameter) are placed in the grinding chamber to obtain improved results.
It takes a tremendous amount of power to operate these grinding mills, and also there are other substantial costs involved. There are a number of factors which relate to the effectiveness and the economy of the operation, and the embodiments of the disclosure are directed toward improvements in such mills and the methods employed.
Disclosed herein are several embodiments of a conjugate anvil-hammer mill. The mill comprises an outer ring, or shell having a substantially cylindrical structure. The structure supported on bearing pads or rollers beneath the shell. The shell rotates about its horizontal axis. The shell defines a chamber where rocks are fed into for comminution. The outer ring in one form has a plurality of (anvil) pockets, attached to its inner surface. The conjugate anvil-hammer mill in one form also has an inner ring located within the outer ring, the inner ring comprising a substantially cylindrical structure. The cylindrical structure may be mounted to a horizontally oriented shaft to rotate about a longitudinal center axis which is offset a distance but parallel to the longitudinal center axis of the outer shell. The inner ring including a plurality of protruding (hammer) elements attached to an outer surface of the inner ring, the plurality of protruding hammer elements configured to each engage one of the plurality of anvil pockets of the outer ring as the inner ring and outer ring rotate in surface unison, wherein material may be inserted into the chamber and crushed between the inner ring and the outer ring with a linear rate of compression. The anvil shell may have slotted openings at the bottom of each pocket to allow sized (crushed) rock to be flushed out of the machine during the anvil-hammer rotation. Since the anvil-hammer centers are offset, their rotation causes a closing action of their surface distances to a minimum gap, at 6 o'clock orientation, where the highest compression stress is applied to the rock. The anvil pocket and hammer protrusion create a surface texture that grabs and captures the rock during their concurrent rotating motion, forcing the rock into a smaller and smaller available gap, as the hammer pushes into the anvil pocket, resulting in slow-steady compression fracture of the captured rocks residing within the anvil pocket.
In some embodiments, the inner ring has protrusions that fit within pockets in the outer ring such that, as the rings rotate in synchronous surface motion, rock or other materials may be crushed between the protrusions and/or pockets of the inner and outer rings, respectively. The surface texture and function of the inner and outer rings may be reversed as certain advantages are realized where the outer anvil ring becomes the protruding hammer, and the inner hammer ring becomes the anvil pocket. Tunnels or ports may be installed between the pocket walls to equalize rock volumes between pockets.
In some embodiments, the inner and outer rings each have surface protrusions, such that rock or other materials may be captured between protrusions and then crushed between the inner and outer rings as they rotate, but their surface outer paths do not cross. In this embodiment, the two rings may be operated at different surface speeds to induce a compression and shearing comminution action. In some embodiments, the inner ring has a circumferential annular ridge that fits within a circumferential annular groove of the outer ring such that rock or other materials may be crushed between the rings, due to the offset centers of the rings. In this way, the rings may operate at differential speeds with respect to each other to induce shear forces, as well as compression action on the material to be crushed. In this later embodiment, the circumferential ridges may have transverse ridges to restrain the rock within shallow annular pockets to capture the rock between the dual ridges that allows a compressive and shear comminution action to be applied to the rock captured between ridges when the inner and outer rings are forced to rotate out of unison. In this later embodiment, ports or tunnels may be applied transverse to the annular rings, at the base of the grooves, to equalize the rock volumes between the annular ridges during the compression cycle.
In the following disclosure, various aspects of a conjugate anvil-hammer mill (CAHM) will be described. Specific details will be set forth in order to provide a thorough understanding of the disclosure. In some instances, well-known features may be omitted or simplified in order not to obscure the disclosed features. Repeated usage of the phrase “in one embodiment” does not necessarily refer to the same embodiment, although it may.
An axes system 10 is shown and generally comprises a vertical axis 12, an anvil radial axis 14 extending radially outward from the center of the anvil ring 22, a hammer radial axis 16 extending radially outward from the center of the hammer ring 28, and a lateral axis 18. The lateral axis 18 is generally aligned with the axes of rotation of the anvil ring 22, and the hammer ring 28. These axes and directions are included to ease in description of the disclosure, and are not intended to limit the disclosure to any particular orientation.
Where possible, a reference system is use comprising a numeric identifier and an alphabetic suffix. The numeric identifier points out a general element and modifications of that utilize an alphabetic suffix. For example, the general anvil ring is identified in
To ensure clarity, rock herein is defined as mineral matter of variable composition, consolidated or unconsolidated, assembled in masses or considerable quantities, as by the action of heat or water. Rock may be unconsolidated, such as a sand, clay, or mud, or consolidated, such as granite, limestone, or coal. While not normally defined as rock, equivalent materials such as hardened concrete may also be used in the disclosed mill.
In
In some embodiments, the inner hammer ring 28 has an outer diameter 52 sized between 50% and 80% of the outer anvil ring 22 inner diameter 50. Another ratio between outer diameter 52 of inner ring and inner diameter of outer ring may be between 0.65 and 0.7. This ratio represents a trade off between (a) a larger inner hammer ring 28 to improve the mechanical crushing advantage and longer wear life of the anvil pocket 36 to crush material, and (b) a smaller inner anvil ring 22 can comminute lighter throughput and be able to crush larger rocks due to the clearance 54 between the rings at the feeding point 56 as shown in the top of
Operation of one embodiment of the CAHM 20 will now be explained. Rock to be crushed is fed into the mill from a chute 58 that guides the material (rock) 38 into the chamber 24 between the outer anvil ring 22 and inner hammer ring 28. Rotation of the anvil ring 22 with the hammer ring 28 conveys the rock 38, by rotation and gravity, into the anvil pockets 36 which then capture the rock 38, as the protruding element 32 applies steadily increasing pressure comminuting the rock 38 within the pocket 36 by way of compression fracture of the material (rock). In this embodiment, the broken rock 38 then passes through the anvil exit grate 60 at the bottom of each pocket 36 or is held therein at which point the crushed rock may clear the retaining shield 40, or may be recycled after breakage for further comminution by the rotating action of the anvil ring 22 and hammer ring 28 in a following pass.
In some embodiments, the pocket wall surfaces 62 of the anvil pocket 36 assist in breaking the rock 38 as the pockets progressively nest with the protruding elements 32 (see
In one example, the hammer ring 28D includes protruding elements 32D which may further include multiple protruding fingers 68 as shown in
The hammer ring 28 in one form is preferably positioned by one or both of a hydraulic cylinder 46 and/or a mechanical adjustment device to achieve the necessary gap 72 between anvil pocket 36, wall surfaces 62, and grates 60; and the hammer ring protrusions 32/hammer valleys 74. One preferable position is achieved when broken rock surface area is maximized for a given power to drive the anvil ring 22 and hammer ring 28. Rock 38 is contained by the moving anvil ring 22 and a stationary shield 40 which has the feed chute 58 passing through its upper sealing zone. In some embodiments, the anvil ring 22 may also have a sealing zone which is positioned outside of the stationary shield 40. Together the shields withhold the rock comminution from escaping the mill 20 at undesired positions.
In some embodiments, once the material is crushed and rotates counterclockwise past a 6 o'clock position 76 (the 6 o'clock position being the position of minimum distance between the two rings as shown in
In another embodiment, the CAHM can also be built to form briquettes as are used in iron ore or other briquetting machines. Instead of pins (protruding elements or pistons) and pockets, the material is filled in dual opposing pockets as it rotates into the high compression zone. In a briquetting embodiment, there may be pockets on either ring and when the rings mate in the high compression zone that the dual pockets form one pocket and make a briquette out of the comminuted fine feed stock and as a separate embodiment discharging matter. A gearing system or other apparatus may be needed to properly align pockets on the anvil ring and hammer ring.
Other embodiments may have different offsets between the pins 80/82, different geometries of pins on either ring, etc.
In some embodiments, the anvil ring 22B and hammer ring 28B may both be mechanically driven. For example, the hammer ring 28B may rotate about an axle that is driven by a motor or other power source, and the anvil ring 22B may rest on a ring and pinion gear system that drives the outer ring by the same motor or engine as the hammer ring 28B, or may be driven by a separate motor or engine. Other dual drive embodiments may be utilized to rotate the rings at synchronized speeds or at differential speeds in relation to each other.
In some embodiments, the protrusions 32 on the hammer ring 28 may be independently and individually fastened to the hammer ring 28, or may be attached to the ring in groups, such as rows, pairs, triplets, etc. These protrusion sets may be fastened by a shear key and a locking device on one or both of the ends of the protrusions or groups of protrusions. For example, the protrusions may be in a set of rows, mounted axially across the surface of the inner ring in relation to the shaft through the ring and each row may have a shear key that fits into a groove in the surface of the ring to support the keys while allowing relatively simple installation or replacement (in comparison to protrusions that are bolted to the hammer ring).
Further, the surface castings 104 on the anvil ring (that create pockets) may be provided in groups as shown in
In one embodiment as shown in
Additionally, the holes 70 in the grates of the outer ring may be sized according to the degree of crushing desired. For example, if it is desired that the largest resultant crushed rock have a maximum diameter of 50 mm then the grates of the apparatus would have an inner diameter (width/length) of 50 mm. Additionally, the holes may have different dimensions in other directions, for example, a hole may have a 50 mm width and a 150 mm length, where the length may be in the direction circumferentially around the inner surface of the outer ring. The gap size in the hole may also be selected to reduce power consumption (as there is a pronounced increase in power consumption for a relatively small percentage change in gap size).
One significant disadvantage of prior art high pressure grinding roll (HPGR) and other crushing mills is that material would often jam between the shield and one or both rollers. In many prior art applications, the shield is static, and does not rotate with either roller, further causing material to jam between the shield and the roller. This problem has been at least partially alleviated herein a shown in
While the present disclosure is illustrated by description of several embodiments and while the illustrative embodiments are described in detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications within the scope of the appended claims will readily appear to those sufficed in the art. The disclosed apparatus and method in their broader aspects are therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicants' general concept.
This application claims priority benefit of U.S. application Ser. No. 13/421,257 filed on Mar. 15, 2012. U.S. application Ser. No. 13/421,257 claims priority benefit of U.S. Ser. No. 61/452,996, filed Mar. 15, 2011. Each of these applications are incorporated herein by reference.
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Number | Date | Country | |
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20150209795 A1 | Jul 2015 | US |
Number | Date | Country | |
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61452996 | Mar 2011 | US |
Number | Date | Country | |
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Parent | 13421257 | Mar 2012 | US |
Child | 14621181 | US |