Patent Application
20100001110
1. Technical Field
This invention generally relates to equipment in the materials processing industry and in particular to a device which breaks mined material into a predetermined desired size range. More particularly, the invention relates to equipment in which larger lumps of material are fractured and broken into smaller pieces by accelerating the material and impelling it against breaker bars. Specifically, the invention relates to a device in which the material is passed through three or more processing regions, where each region includes an inclined surface along which the material travels, a variable speed rotor for accelerating the material in the direction it was traveling and a breaking surface for fracturing the material into smaller pieces.
2. Background Information
Mined materials comprise a mixture of rocks and minerals. This presents a problem to a materials processor in that they need to separate the desired materials from the non-desired materials. In the coal mining industry, for example, the mined material will include a quantity of coal and a quantity of rock. The rock, which cannot burn, is regarded as an impurity that needs to be separated from the coal before it can be sold. The actual quantity of impurities in any given sample of mined material may vary from a reasonably small fraction to a substantial fraction. It is necessary to process the mined material in such a way as to be able to separate the desired material from the impurities in the most efficient and cost effective manner. Furthermore, depending upon the final use for which the desired material is intended, it may be necessary to break larger lumps of the material into smaller pieces of a predetermined size range. For example, pieces of coal that are two inches in diameter and smaller are commonly used in many burning applications. Consequently, if the mined material includes coal lumps that are greater than two inches in diameter, it would be necessary to break those larger coal lumps down to the desired size range of two inches and smaller.
Materials processors have utilized a variety of methods to break down larger lumps of mined material into a desired size range and to separate the desired material from the impurities. These methodologies have included attrition, where the larger material lumps are scrubbed between two opposing hard surfaces, shear where smaller sections of larger material lumps are broken off, compression where the larger material lumps are crushed between two surfaces, and impact where the larger material lumps are forced to collide with an object in order to break it up.
A variety of different machines have been developed that employ these methodologies in various combinations. Such machines have included rotary roller crushers in which the mined material is passed between and is crushed by counter-rotating rollers. Rotary breakers have also been used. These machines include a large, hollow rotating drum that includes a plurality of interior baffles to break up the material lumps as they are tumbled within the drum. Hammer mills have also been employed for crushing materials. Hammer mills include a hammer-type device that impacts the mined material resting on a surface and crushes the same. All of these prior art devices process the desired material and the impurities in the same manner and substantially to the same degree. Consequently, larger lumps of both the desired material and the impurities are broken down into smaller pieces by the machinery and it therefore becomes more difficult to separate the desired material from the impurities by size and further processing is required.
Furthermore, these previously known machines are typically located at a material wash plant which may be some distance from the mine or pit. All of the mined material, which contains both the larger material lumps and the impurities, must be transported from the mine to the processing site. After processing, the removed impurities must either be returned to the original site or be transported to a disposal site. Wet processing of material exacerbates handling issues and creates a variety of environmental concerns. All of these issues increase the cost of recovering the desired material.
While all of these previously known breakers perform satisfactorily, they require a considerable amount of energy to rotate the crusher rolls, to rotate the drum or operate the hammer-type device. Furthermore, it is difficult to adjust the machinery to cause different size material pieces to be produced. It is also difficult to correlate the breaking force produced by the machine to the hardness of the particular seam of material being broken down by the equipment.
In addition to the previously discussed equipment, several types of material breakers employ rotors which propel the lumps of mined material against impact surfaces in order to break the larger lumps into smaller pieces. Examples of these types of breakers are shown in U.S. Pat. Nos. 2,110,850 and 2,192,606. Although these breakers perform satisfactorily, they require a relatively large motor and increased power because of the heavy structural members utilized therein and because the rotors are used to change the direction of the material lumps being broken down. In addition to propelling the material lumps and increasing the speed thereof for impact against a surface, the rotor blades are also used to perform some crushing or shearing of the material lumps. The previously known machines also do not remove the desired size material pieces from the processing flow of the machine as soon as possible after production thereof. Consequently, both the larger and smaller sized material pieces tend to remain in the breaker for a longer period of time. This tends to result in an increased quantity of the desired size pieces being further reduced in size, thereby reducing the quantity of saleable product. Additionally, the over-processing of the material increases the quantity of small particles or particulates that are produced by the equipment. In the coal processing industry these particulates are known as fines. Fines are typically more difficult to process and handle and the production of excessive quantities of the same is undesirable.
This issue was addressed in U.S. Pat. No. 4,592,516. This patent is assigned to the present assignee and the entire specification thereof is incorporated herein by reference. The patent discloses a device for breaking larger coal lumps into predetermined size coal pieces and separating those desired size pieces from the rock fraction before the coal is over-processed and broken down into fines.
The mined material is introduced into a hopper at the top of the machine and travels down a zigzag pathway. Along the pathway, the larger lumps of mined material are broken down by accelerating them and impacting them against appropriately positioned components. The pathway includes a first inclined scalping grizzly positioned proximate a first rotor. The rotor engages the larger lumps in the same direction in which they were traveling through the machine and accelerates them so that they strike against a first impact grid. Coal is typically softer and more friable than the rock fraction of the mined material. Consequently, when larger lumps of material strike the first impact grid the coal tends to fracture but the harder rock does not. Smaller pieces of coal break off the larger lumps when the larger lumps impact the first impact grid. The harder rock pieces tend to stay intact. The first impact grid includes a plurality of openings that allows coal pieces of a predetermined size and smaller to pass therethrough.
The portion of the mined material that did not pass through the openings in the first impact grid drops onto the inclined second scalping grizzly. Since the second scalping grizzly also contains openings therein, pieces of coal and rock that are of the predetermined size and smaller that did not pass through the openings in the first impact grid pass through the openings in the second scalping grizzly. This occurs before the smaller coal pieces encounter a second rotor. The desired size pieces of material are therefore removed before they can be accelerated into a second impact grid. This effectively prevents the desired size coal pieces from being further processed and broken down into fines.
Any larger pieces of the mined material that are unable to pass through the openings in the second scalping grizzly continue down the same and encounter the second rotor. The second rotor engages these pieces of material and propels them against the second impact grid. Once again, smaller pieces of coal are fractured off the larger lumps, while the rocks remain relatively unbroken. The second impact grid includes openings that allow any materials that are of the predetermined size and smaller to pass therethrough. The mined material that did not pass through any openings in either of first and second scalping grizzlies and first and second impact grids drops through a discharge opening at the base of the machine and exits the machine. Likewise, the predetermined size coal pieces and rocks that passed through the openings in the first and second grizzlies and first and second impact grids are also discharged from the machine. The discharged material is then screened to recover the desired size coal pieces.
In the device disclosed in U.S. Pat. No. 4,592,516, the speed of the rotors is adjusted to suit the hardness of the coal being processed. Harder coals require relatively higher rotor speeds to break up the coal lumps than do softer coals. For example, a hard coal may require a rotor speed of around 400-420 rpm to break the coal into smaller pieces, while a softer coal may only need a rotor speed of around 200-350 rpm.
While the device disclosed in U.S. Pat. No. 4,592,516 functions extremely well in some applications, it has been found that problems arise when larger lumps of material must be processed by the machine or when a smaller end product is desired. If the lumps are larger, the first and second rotors have to be rotated at a much higher rotor speed than would be warranted if the lumps were smaller. These higher rotor speeds have the undesirable side effect of shattering a greater percentage of the desired material into particulates. Additionally, a greater percentage of the impurities are broken down into a size that will pass through the openings in the scalping grizzlies and impact grids. Thus, the end product contains a lower quantity of the desired size material, a higher quantity of particulates and a higher quantity of impurities. The end product is therefore less saleable. This problem is exacerbated even further if the material is relatively hard.
An additional problem caused by rotating the rotors at higher speeds is that the production of additional particulates in combination with the air flow generated by the rotors tends to result in a large quantity of dust being blown out of the machine and into the surrounding area.
Accordingly, there is a need in the art for an improved material breaker that is able to break down larger sized lumps of material into pieces of a predetermined smaller size while producing fewer particulates and generating less dust than in previously known machines.
The device of the present invention comprises a material breaker for breaking larger lumps of material into a smaller saleable product. The device processes these larger material lumps in a manner that tends to produce a fewer particulates and less dust. Additionally, the device and method tends to break down the large lumps of material without breaking down an increased percentage of impurities that would contaminate the end product. Furthermore, the device is designed to be operated at any location, but is most desirably operable at the mine or point of material generation itself, thereby reducing the costs involved with transporting undesirable impurities.
The breaker of the present invention includes a series of processing regions for splitting large diameter material lumps into pieces of a greatly reduced size. Specifically, the system includes three or more processing regions that are disposed in series with each other. In a first embodiment of the system, the three or more processing regions are disposed vertically one above the other. In a second embodiment of the system, the individual processing regions are linked to each other by way of conveyors or other transport mechanisms and may be disposed vertically relative to each other or horizontally relative to each other.
In accordance with one of the specific features of the present invention, each of the processing regions includes an inclined scalping grizzly, a rotor and an impact grid. All of the scalping grizzlies and impact grids have a plurality of openings therein through which pieces of the predetermined desired size may pass. The rotor in each processing region engages the lumps that are on the scalping grizzly and accelerates them toward the impact grid. When the larger lumps of material strike the impact grid, they are fractured and smaller pieces of the material break off the larger lumps.
In accordance with the present invention, the speeds of the first, second and third rotors are substantially reduced relative to previously known devices for processing materials of like nature. More specifically, the speeds of the first, second and third rotors are substantially reduced relative to the two rotors utilized in the machine disclosed in U.S. Pat. No. 4,592,516 for processing materials of like nature. The lower speeds are made possible by the presence of the additional processing regions that present extra opportunities for the larger lumps of material to be fractured. These substantially lowered speeds result in a higher yield of the desired size material pieces than in previously known machines. Additionally, the lower speed of rotation of the rotors results in a decrease in the quantity of particulates or fines produced and a decrease in the quantity of impurities of a size that can pass through the openings in the scalping grizzlies and impact grids. The device therefore produces a higher quality end product. Additionally, the system produces less dust than previously known machines because the rotors are rotating at lower speeds.
In the device of the present invention, the range of speed of operation of the first rotor in the first processing region is lower than would be the case if the system only included the two processing regions with two rotors disclosed in U.S. Pat. No. 4,592,516. By way of example only, the speed of the first rotor could be set at anywhere in the range of between 200 rpm and 250 rpm depending on a variety of factors. It will be understood that the rotor speed is set according to the nature of the mined material being processed in the breaker. So, for example, the speed of the first rotor would be set lower for softer materials and higher for harder materials. The rotor speed would also be determined by the size of the large lumps of material that are to be introduced into the first processing region and the desired end size of the materials being processed. So, for example, if the large lumps of material are to be broken down into a 1″ diameter size, then the speed of the first rotor might have to be set higher than would be the case if the size of the end product was to be 2″ in diameter or smaller.
Similarly, by way of example only, the speed of the second rotor in the second processing region could be set in the range of between 250 rpm and 300 rpm, and the speed of the third rotor in the third processing region could be set at somewhere between 300 rpm and 350 rpm.
Another objective of the invention is to provide a device in which the rotors are rotated at a speed sufficient not to accelerate the larger lumps of material at a velocity that will cause them to shatter in such a way as to produce excessive fines. Instead, the rotors are rotated at a speed sufficient to accelerate the large lumps of material at a velocity that will cause them to fracture in such a way as to maximize the desired size range of material pieces while producing a smaller quantity of fines.
A further objective of the invention is to provide such a construction in which the motors for driving the accelerator rotors are variable speed rotors that permit the speed to be adjusted depending on the hardness and friability of the material that is being split and sorted at a particular time. This variability enables more accurate control of the impact breakage effect of the improved device by a convenient adjustment of controls located on an electrical or hydraulic control panel.
Another objective of the invention is to provide such a material breaker construction in which the material, upon being reduced to the desired size range, is removed as soon as possible from within the system. This eliminates further breakage of the material and thereby reduces the quantity of fines that was common in prior breaker and crusher constructions.
The preferred embodiments of the invention, illustrative of the best mode in which applicant has contemplated applying the principles, are set forth in the following description and are shown in the drawings and are particularly and distinctly pointed out and set forth in the appended claims.
Referring to
Passageway 22 includes a first inclined scalping grizzly 34, a first inclined metal plate 36, a first impact grid 38, a second inclined scalping grizzly 40, a second inclined plate 42, and a second impact grid 44. A first accelerator rotor 54 is provided in passageway 22 proximate first scalping grizzly 34 and a second accelerator rotor 56 is provided in passageway 22 proximate second scalping grizzly 40. The breaker disclosed in U.S. Pat. No. 4,592,516, included these components.
In accordance with a specific feature of the present invention, passageway 22 further includes, a third processing region in which the mined material is further broken down into smaller size pieces. The third processing region includes a third inclined scalping grizzly 46, a third metal plate 48, and a third impact grid 50. In accordance with a further feature of the present invention, a third accelerator rotor 58 is provided in passageway 22 proximate third scalping grizzly 46. Although not illustrated in
Referring still to
Each of the first, second and third scalping grizzlies 34, 40 and 46 are substantially identical in structure and function. First scalping grizzly 34 is shown by way of example in
Each of the first, second and third rotors 54, 56 and 58 are substantially identical in structure and function and the speed of each rotor may be varied as necessary to break down the mined material. First rotor 54 is shown by way of example in
The first, second and third impact grids 38, 44 and 50 are all substantially identical in structure and function. First impact grid 38 is shown by way of example in
The operation of improved material breaker is best understood by reference to
In the breaker, the material 80 passes from conveyor 20 onto first scalping grizzly 34 of the first processing region and then moves down the inclined grid 34 under the influence of gravity. Any material pieces and impurities of a size smaller than the openings 68 in first scalping grizzly 34, such as pieces 82, will pass through openings 68 in first scalping grizzly 34 and into first chute 26. Pieces 82 fall downwardly through first chute 26 until they contact plate 84 at the base of hopper 10. Plate 84 directs pieces 82 through discharge opening 24 and onto conveyor 32. (It will be understood, that instead of conveyor 32, a screen or hopper could be positioned beneath discharge opening 24. Alternatively, the discharged material could simply drop onto the ground beneath the breaker. ) This immediate removal of predetermined size pieces 82 from the first processing region prevents them from being further reduced in size.
The remaining larger material lumps 86 and any impurities present that are too large to pass through openings 68 continue to roll down inclined first scalping grizzly 34. First rotor 54 is rotating in the direction indicated by the arrow A. When flails 72 contact lumps 86, the lumps 86 are caused to accelerate in generally the same direction in which they were traveling down first scalping grizzly 34, i.e., in the direction of travel indicated by arrow B. This propulsion in the same direction requires considerably less power for operating first rotor 54 than if the material lumps were struck by a rotor which changed the particle's direction of travel. The accelerated material lumps 86 impact first impact grid 38 and are split by pointed plates 76. Any pieces that are of a size that enables them to pass through openings 78 (
The remaining materials including material lumps 86 and impurities pass from the first processing region into the second processing region by dropping from the first impact grid onto inclined second scalping grizzly 40. Once again, if any of the predetermined sized pieces 82b and smaller are present in these mined materials, they pass through openings 68 in second scalping grizzly 40 and into second chute 28. The remaining larger material lumps 86 and impurities are struck by flails 72 of second rotor 56 and are accelerated in the same direction in which they were traveling, i.e., in the direction of arrow C. The accelerated material lumps 86 and impurities are thrown against second impact grid 44 and are split by pointed plates 76 thereon. Many of the predetermined sized pieces 82 pass through openings 78 (
The remaining material lumps 86 and impurities move from the second processing region into the third processing region by dropping from the second impact grid onto the third inclined scalping grizzly 46. Any predetermined size pieces 82 and smaller that are mixed in with material lumps 86 pass through openings 68 in third scalping grizzly 46 and into first chute 26. The larger lumps 86 continue to roll downwardly along third scalping grizzly 46 until they are struck by flails 72 of rotating third rotor 58. Third rotor 58 accelerates the material lumps 86 and impurities in the same direction in which they were traveling, i.e., in the direction indicated by arrow D. Lumps 86 are thrown against third impact grid 50 and are split yet again by pointed plates 76 thereon. Once again, some of the predetermined size pieces 82b pass through openings 78 (
The fact that there are at least three rotors 54, 56, 58 in hopper 10 enables the breaker to break down larger material lumps to into the desired size pieces and smaller with the rotors moving at lower speeds of rotation than in previously known machines. Furthermore, the lowered speeds cause the larger lumps of material to be fractured on the pointed plates 76 instead of being shattered, thereby reducing the quantity of fines produced by the breaker. The speeds are also typically not high enough to cause rocks, minerals and other impurities contained in the material to be split by the impact grids to a size sufficient to permit them to pass through the openings in the scalping grizzlies and impact grids. Consequently, these impurities tend to travel all the way down to the bottom of the zigzag passageway 22 through the machine where they are more easily separated from the material discharged through discharge opening 24.
As was the case with the device disclosed in U.S. Pat. No. 4,592,516, the rotational speeds of first, second and third rotors 54, 56 and 58 of the present invention are adjustable to match the particular hardness of the material 80 fed into inlet opening 18. The rotational speeds are adjusted until the larger material lumps 86 are mainly fractured instead of completely shattering or splitting into very small pieces when they strike the impact grids. If the lumps 86 are not being accelerated fast enough and are therefore not being sufficiently split by the process, the rotational speeds of the rotors is increased. If the acceleration of the material lumps is too great, then the quantity of fines being produced and impurities broken down by the process will be excessive and the rotational speeds of the rotors is reduced. The speed of the first rotor 54 is set to be sufficient to engage the large lumps of material and accelerate them toward the first impact grid 38. The speed of this first rotor 54 must be high enough to only fracture the large material lumps instead of shattering them. Essentially, the first rotor 54 is simply used to break the lumps into a more manageable size. The second rotor 56 may be rotated slightly faster than the first rotor 54 and the third rotor 58 may be rotated slightly faster than the second rotor 56. The operator sets the impact velocity of rotors 54, 56 and 58 by adjusting the speed of the drive motors. The velocity is adjusted to match the individual material seam being processed simply by turning a potentiometer dial.
The lowered speed of rotation of rotors 54, 56 and 58 relative to previously known devices has the side benefit of also reducing the friction and wear and tear on the rotors, impact grids, and other components in the system, thereby prolonging the life of the device and reducing the frequency of maintenance thereon.
The improved material breaker is preferably located and used on the site to separate and size the material immediately after being produced. This eliminates the need to transport the material, including the impurities, to a remote location and then transporting those impurities on to a dump site or pit. If a source of electrical energy is not available at the site, the electrical motors can be replaced easily by hydraulic motors run by a portable generator. Such hydraulic motors would be connected directly to the output of the rotor shafts eliminating the drive belts and associated sheaves. Likewise the unit can be modified for producing different size material pieces by replacing the inclined scalping grizzlies and impact grids with similar equipment having the desired size openings formed therein.
Accordingly, the improved material breaker construction provides an effective, safe, and efficient device which achieves all of the enumerated objectives, provides for eliminating difficulties encountered with prior devices and solves problems and obtains new results in the art.
In the device of the present invention, the inventor has recognized that the rotors can be rotated at lower speeds as each successive processing region in the breaker provides an additional opportunity for pieces of material to be fractured off of the larger lumps. Because the rotors are moving at a lower speed, the larger lumps of material are not accelerated toward the impact grids with the same velocity as they would be if the rotors were moving at higher speed. Consequently, when the larger lumps of material strike the impact grids they are fractured without producing the large quantity of particulates, or fines, as would be the case if they struck the impact grid at a higher velocity. Additionally, the lower speed rotors generate less wind blowing out of the breaker than would be the case if the rotors moved at a higher speed. Consequently, the quantity of dust blown out of the breaker is much reduced. Furthermore, the inventor has recognized that it is possible to include more than three processing regions in the breaker so that the system can be used to process much larger lumps of material than was possible in previously known devices.
In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed.
Moreover, the description and illustration of the invention is by way of an example and the invention is not limited to the exact details shown or described.
Having now described the features, discoveries and principles of the invention, the manner in which the improved material breaker construction is constructed and used, the characteristics of the construction, and the advantageous, new and useful results obtained; the new and useful structures, devices, elements, arrangement, parts, and combinations are set forth in the appended claims.
This application claims priority from U.S. Provisional Application Ser. No. 61/133,929 filed Jul. 3, 2008; the disclosure of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61133929 | Jul 2008 | US |
