US2981489A - Reduction apparatus - Google Patents

Description

April 5, 1961 w. B. HANNUM, JR 2,981,489

REDUCTION APPARATUS Filed Feb. 15, 1960 2 Sheets-Sheet 1 FIEZ.

INVENTOR WILLIAM B. HANNUM, JR.

w. B. HANNUM, JR 2,981,489

April 25, 1961 REDUCTION APPARATUS Filed Feb. 15, 1960 FIEE.

2 Sheets-Sheet 2 INVENTOR: WILLIAM B. HANNUM, JR.

BY WW REDUCTION APPARATUS William B. Hannurn, Jr., Green Tree Road, Paoli, Pa. Filed Feb. 15, 1960, Ser. No. 8,643

9 Claims. (Cl. 241-275) The application which matured into this patent is a continuation-in-part of my earlier filed U.S. application, Serial No. 693,754, filed October 31, 1957 and now abandoned.

The present invention relates to improvements in apparatus for reduction in particle size of materials such as ores, cement, clay and the like and more particularly to apparatus wherein the reduction of the materials into smaller particles is accomplished largely by attritionand impact of the particles against one another.

The present invention is directed to piece or particle size reduction apparatus in which materials are ground and crushed by their action upon one another. This action is due primarily to fracturing of the particles by impact upon other similar particles which may simultaneously be broken. The apparatus is extremely simple and employs relatively few parts which are easily fabricated and which are assembled with a minimum of labor and equipment. The weight and size of the parts of the apparatus, furthermore, has been materially reduced over conventional crushing apparatus. The order of weight reduction has been conservatively said to be manyfold for devices of the same capacity over the types of apparatus in which the weight of heavy elements has been relied upon to accomplish the crushing. This is particularly true since the efiiciency of older types of mills is usually attributed to the weight of the crushing elements (e.g., hammers, balls, etc.). Additionally, the apparatus of the present invention is extremely efiicient and by the very nature of its operation avoids undue wear of parts. The equipment is not subject to appreciable wear due to the fact that crushing and grinding occurs between particles being treated rather than at surfaces of the equipment. This factor is quite important from the standpoint of purity of product, and the product of this machine has proved to contain far less contaminants than comparable products otherwise would.

The present invention in its broadest form consists of an inner impeller and an outer hollow rotatable member both of which members have vertically oriented axes of rotation. Means is provided to drive the impeller where by centrifugal force will eject its particles outwardly toward the inner wall of the hollow rotatable member. The walls of the hollow rotatable member are upwardly divergent from the region of impact so that rotation of the hollow member will not only hold the particles in place but cause them to move upwardly toward the upper edge or lip of the hollow outer member. Before the particles can pass over the lip and out of the grinder, however, they must pass classifying means which is spaced from the inner wall of the hollow member above the region of impact. Those particles which are too large are caught by the classifying means and allowed to fall back by gravity into the impeller. Preferably suitable funnel means is provided to guide the material to the center of the impeller.

One feature of great advantage in the apparatus of the present invention is the ability to recirculate particles nited States Patent 17 above the reduction apparatus.

2,981,489 Patented Apr. 25, 1961 within itself and by its own action until they are reduced to a desired predetermined size. This may be absolutely or relatively so depending on the type of classifying means selected. Thus, within a very small region particles may be ground to controlled fineness of almost any desired degree. By employing the annular groove on the inside wall of the outer hollow member, in addition to great efliciency the advantage of high purity of product is assured since wear is reduced to a point where it is negligible.

With the foregoing in mind, an object of the present invention is to provide an apparatus and method for reducing coarse particles of material wherein the reduction is accomplished by a fast and efiicient operation and wherein the particles may be comminuted to a small particle size.

Another object is to permit controlled reduction in size to any degree of fineness desired.

Another object is to provide internal circulation and recirculation within a region relatively limited in size.

Another object is to provide an apparatus of relatively simple and inexpensive construction wherein the expeditious and eflicient reduction of particles is accomplished with a minimum amount of wear of the apparatus.

These and other objects of the present invention and the various features and details of the operation and construction of an embodiment thereof are hereinafter more fully set forth and described with reference to the accompanying drawings, in which:

Fig. 1 is a front elevation of associated structure which may be used with the present invention;

Fig. 2 is a longitudinal cross section of an embodiment of the present invention;

Fig. 3 is a top elevational view taken along line 3-3 of Fig. 2 illustrating the construction of the impeller;

Fig. 4 is a sectional view taken along line 4-4 of Fig. 2;

Fig. 5 is an enlarged fragmentary sectional view showing the discharge of the material from the impeller and the impact of the material against a layer of material formed on the bowl; and

Fig. 6 is an exploded fragmentary perspective view of one of the vanes of the impeller unit.

Fig. 1 shows one possible environment for the reduction apparatus of the present invention. In the system illustrated it is presumed that some of the material which leaves the reduction apparatus will be oversized and be turned for further reduction. However, it is possible to eliminate the need for the recirculation system in certain embodiments of the present invention, which are so arranged that only material which is sufiiciently reduced can leave the reduction apparatus.

Referring more specifically to Fig. 1 reference numeral 10 designates generally a material particle size reduction apparatus in accordance with the present invention The apparatus is shown within a size classifying and recirculating system having a cylindrical housing 11 which surrounds the apparatus and which terminates at its lower end in a converging collecting funnel 12. Associated with the collecting funnel is a screening device for removing sufficiently reduced particles. This screening device consists of a screen '13 agitated through a suitable transmission means by a motor 14. A collector bin 15 for finally processed material is positioned under the screening apparatus to receive particles of material sufficiently fine to pass through screen 13. From the bottom of the collecting funnel 12, a conveyor system 16 carries a material to be reprocessed back to a hopper A slide 18 feeds new material also into the hopper. The hopper -17, in turn, feeds its contents into the reduction apparatus through a chute 19.

Fig. 2 illustrates the apparatus of the invention, which is shown in section so that the internal structure may be seen in detail. An outer hollow member, in this case relatively shallow bowl constitutes a primary element of the system. Where the system of Fig. 1 is employed, the hollow outer member 20 is mounted in the housing preferably substantially concentric therewith. The outer hollow member is provided with drive means which causes it to rotate in one direction at a relatively low speed about its axis of symmetry which is vertically oriented. In the embodiment shown, bowl 20 is supported on its drive means which, in turn, is supported on beams 36 extending across the housing and attached thereto. The drive means here is a motor 21 connected to the bowl 20 by a vertically oriented shaft 22 which supports the bowl as well as imparting rotation to it. The bottom of the outer hollow member need not be closed, but advantages are obtained by having it closed or providing a ledge below the region of impact to catch particles which drop when rotation stops. In the bowl embodiment the bottom of the bowl slopes gradually into the side walls. The side walls of the hollow member whether or not a bowl preferably diverge upwardly and outwardly, the divergence continuing to the lip even if only a few degrees or less. Divergence is particularly important above a concave annular groove 23 in the inner wall of the hollow member and spaced below the lip.

An impeller structure 24, preferably having a vertically oriented axis of rotation preferably in common with the central axis of the hollow outer member, extends downwardly into the bowl. The impeller structure 24 has associated drive means which rotates the impeller at a relatively high speed, preferably in a direction opposite the direction of rotation of the bowl. The drive means here is a motor 25 mounted on the housing, or its associated support structure, and is connected by a belt transmission 26 to a shaft 37 which drives and mechanically supports the impeller. The shaft is journaled in a bearing member 27 of a supporting structure 28 which may also furnish support for the housing. The impeller structure comprises a platform 29 atfixed to the end of shaft 37 and preferably providing a substantially flat surface perpendicular to the shaft and generally horizontally arranged. Its top surface may be provided with a plurality of vanes 30 which may be adjustable outwardly toward the inner wall of the hollow outer member. The vanes 30 may be slightly curved as shown in Fig. 6, or curved in the opposite direction, or need not be curved, and may be directed radially or spirally outwardly. However the vanes need not be used. It is preferred to use an adjustable structure such as shown in Fig. 6, however. Therein there are fixed vanes 300 which may be riveted to the platform and adjustable vanes 30b movable relative to the fixed vanes and the platform. Their L-shaped cross section provides flanges by which they are fixed to the impeller platform 29. They may be nested as shown with movable piece 30b within and on top of fixed piece 30c. The support flange of movable vane portions 300 have slots 30d which permit sliding of portion 300 in the direction of slots 30d when their connecting bolts 30a are loosened. The impeller structure is preferably disposed in substantial transverse alignment with the annular groove or channel 23 in the side walls of the bowl.

An inverted open-center frusto-conical funnel 31 supported by posts 32 from the top portion 33 of the housing extends down into the bowl and directs particles which fall upon it from above to be funneled into the impeller adjacent the hub. Well above the impeller at the periphery of the shell a horizontally disposed flange 34, an extension of funnel 31, provides support for a plurality of scrapers (see Fig. 4) atop the flange 34 in substantially equispaced relation as shown s side walls of the bowl by centrifugal force.

in Fig. 5. The scrapers 35 are positioned above groove 23 or the area of particle impact at the upper extent of the bowl and preferably just below the lip of the bowl. The upper extent of the bowl will be understood to refer to that region spaced above the impact region which lies opposite scrapers 35 whether or not the sidewalls extend above this region. The scrapers have a general orientation toward the bowl walls and preferably are arranged relative to bowl wall at an obtuse angle with bowl wall surfaces moving toward them to provide a shovel effect. They may be adjustably supported on flange 34 in much the same way as the vanes of the impeller are mounted on impeller plaform 29 but using suitably heavier construction. Preferably the construction includes angle iron members 35a and 35b arranged back to back with members 35a fixed to flange 34 and members 35b each provided with a threaded stud which projects through a slot in member 35a so directed that member 35b can be adjusted inwardly and outwardly. Adjustable mounting on the flange 34 provides a variable clearance between the inner wall of the bowl and the outer edge of the scrapers in order to afford adjustment of the gap between the scrapers and the bowl. Adjustment of the scrapers permits change of the maximum size of particles which can pass between the scrapers and the side walls. The scrapers are optional and may be omitted if other classifying means is used or used in tandem with other classifying means.

Another type of classifying means is cover 38 which is provided at the upper edge of the hollow outer memher. It serves to prevent particles larger than the annular space or annulus between its periphery and the edge of the bowl from leaving the bowl. In preferred embodiments as shown it can be vertically adjusted by loosening set screws 39 in collars 40 which are afiixed to cover 38 and slide on posts 32. In some embodiments the cover is movable into the bowl. In other embodiments it is cooperable with the upper edge or lip rather than the inside wall. In either event it serves to limit the particle size of material leaving the bowl, and where used can eliminate the need for the complete system of Fig. 1. It is particularly effective where used in combination with scrapers, as shown, or other means which recirculates the larger particles, leaving primarily fines for classification by cover 38. Since it is primarily the peripheral or outer edge which is effective in classification, the cover may, instead of being essentially continuous as shown be merely a ring or be perforated as desired.

Two types of classifying means either of which can be used alone or in combination with each other or other types of classifying means have been described. These are merely representative of classifying means, however, and it will be understood that there may be modified and, in fact, entirely different types of classification means may be used within the scope of the present invention. It is the essence of the invention, however, that the classifying means function to cause oversized particles to be repeatedly recirculated within the reduction apparatus itself until reduced to desired size. Preferably this recirculation is due to means which mechanically intercept the oversized particles and permits them to fall by gravity back into the impeller structure. The general operation of the apparatus can best be described with initial reference to Fig. 2. Before operation begins a quantity of material is preferably placed in the bottom of the bowl or atop suitable means retaining it against gravity below the groove. Alternatively material may be fed upward through a suitable access opening in the lower portion of the bowl at the start of operation. The bowl is started before material is fed to the impeller. Due to the rotation of the bowl and the upward divergence of its side walls the particles of material are urged upwardly along the Preferably only after the particles fed from below have filled the annular groove, the impeller is started and material is fed to the impeller from the hopper either as new material from slide 18 or as material to be reprocessed from conveyor 16. The conveyor must also be started if such a system is used. The material is fed from the hopper 17 through the chute 19 to the reduction apparatus.

As seen in Figs. 4 and 5, the material to be ground is directed by the chute 19 into the impeller 24 near the hub. Centrifugal force moves the particles on the impeller outwardly and they tend to increase in velocity with the impeller as they progress. They leave the edge of the impeller at approximately its velocity and are thrown against particleson the inner side walls of the hollow member held in place by centrifugal force. The impact of ejected particles on particles held against the wall causes fracturing of the particles ejected as well as particles on the wall. Thus, the major portion of the reduction process is accomplished by an attrition of particles on themselves. Preferably the particles on the wall are held in a thick pad by a groove which traps them as they move up the wall. By use of the groove the machine may be designed so that little or no wear of the machine occurs and the ground product is not contaminated but is highly 'pure.

It will be observed that the annular groove serves to hold particles by centrifugal force against the bowl wall exactly in the region of impact. The annular groove serves the two-fold purpose of providing a suflicient thickness of material in the region to protect the bowl wall against wear and of avoiding the need of continuous feed from the bottom of the bowl. To avoid continuous feed it is merely using the groove necessary to provide suflicient material in the bottom of the bowl at the start of operation to fill the annular groove as particles move upward and outward. The device by its very nature will provide the needed amount of material from that which falls out of the groove upon completion of an operation and the stopping of the bowl. By making the groove in the diverging side wall particles from below which move up under centrifugal force are inevitably trapped in the grooves larger diameter and until the groove overflows, particles which fall in the groove or below cannot move higher along the upwardly diverging walls.

In other modifications of the invention the groove may be omitted, but in that event feed along the bowl wall must be effective continuous if wear and/ or contamination of the product are to be avoided.

The particles are forced upward along the slightly diverging walls of the bowl from the region of major reduction by centrifugal force as the result of overflow from the groove 23 upon the arrival of additional particles, whether from the bowl or impeller. The amount of divergence of the walls above the groove may be selected for any desired rate of particle removal, and is preferably able to keep the particles moving at such a rate that the side walls are covered only to a single particle thickness. As the particles travel upward along the bowl wall they must pass the scrapers 35 whose adjustment with respect to the inner wall of the bowl will determine the maximum size of the particles which in general may pass. Particles larger than this spacing will be removed and returned via funnel 31 to the impeller.

A coverplate of the type shown acts to stop movement of the particles so that they are not held against the outer hollow member by centrifugal force but fall under gravity back into funnel 31 which feeds the impeller. The particles which pass the scrapers and the coverplate pass over the edge of the bowl. If the coverplate is used the particles are not subject to further processing in the system of Fig. 1.

If processing is not complete upon leaving the reduction apparatus the system of Fig. 1 may be used, in which event the material falls into funnel 12 and passes over classifier screen 13. The classifier sifts sufficiently finely divided material into collector bin 15 and the larger particles fall to the bottom of tunnel 12 and are picked '6 up by the conveyor 16. The conveyor returns the larger particles to the hopper to be reprocessed.

The present invention is adaptable to a wide range of sizes, and the speeds of rotation of the impeller and the bowl are to some extent dependent upon size as well as such factors as the hardness of the material to be reduced. The bowl speed must be sufiicient to bring the particles up the walls of the bowl to the region of reduction. The impeller speed must be suflicient to impart enough outward linear speed to the particles to enable them to do their work, and the minimum speed required varies with the material used. In one embodiment where the impeller was about 12 inches in diameter a bowl having a diameter of 16 inches in the region of reduction was employed. The bowl was driven at about 200 rotations per minute and the impeller performed satisfactorily for a variety of materials at approximately 1700 and 3500 rotations per minute.

The method and apparatus described are applicable to the grinding of a slurry as well as dry material. However, when processing a slurry there exists the possibility of clogging or congestion in certainvital areas such as the region of impact. The apparatus, therefore, may be modified for use with a slurry by the provision of a suitable wiper which may be either stationary or revolving and which serves to remove material from the region which tends to clog.

From the foregoing it will be apparent that the present invention provides a novel improvement in grinding apparatus wherein comminution of the particles is accomplished by the impact of the particles so that the bulk of the wear is absorbed in the particles and not in the various parts of the apparatus and wherein the attrition is accomplished expeditiously and economically.

While a particular embodiment and modifications thereof have been illustrated and described herein, it is not intended to limit the invention to such a disclosure and changes and modifications may be incorporated and embodied therein within the scope of the following claims.

I claim:

1. Apparatus for reducing particle size of material comprising an inner impeller rotatable about a vertical axis, drive means for the impeller adapted to cause rotation to eject material radially outwardly, a hollow outer rotating member having a vertically oriented axis of rotation, an impact region opposite the impeller against which material is ejected, and continuous sidewalls upwardly and outwardly divergent above the impact region to their upper extent, drive means for the hollow outer member to rotate it at sufficient speed to cause upward movement of particles by centrifugal force along the sidewalls above the impact region, and particle recirculation means adjacent the upper extent of the sidewalls above the impeller cooperative with the hollow outer member relative to which the hollow outer member rotates arranged proximate to the walls of said outer member and so constructed and arranged that it mechanically intercepts material moving up the sidewalls and diverts it back toward the center of the impeller so that it will fall into the impeller by gravity.

2. The apparatus of claim 1 in which the particle recirculation means includes funnel means below the upper extent of the sidewalls but above the impeller and so constructed and arranged that it collects material falling back under gravity from the means adjacent the upper extent of the sidewalls to the center of the impeller.

3. The apparatus of claim 2 in which scrapers are outwardly directed toward the sidewalls of the outer hollow member adjacent its upper extent and so constructed and positioned as to intercept and divert inwardly some of the larger particles of material moving up the sidewalls and thereby provide parts of the recirculating means.

4. The apparatus of claim 3 in which the scrapers are adjustable toward and away from the sidewalls to permit modification of the particle size permitted to leave the reduction apparatus.

5. The apparatus of claim 1 in which the impact area is provided with a material retaining groove fixed relative to the hollow outer member and so constructed and arranged to retain due to centrifugal force the material which fills the groove and the overflow from which groove flows onto and move up the upwardly and outwardly divergent sidewalls of the hollow outer member.

6. The apparatus of claim 1 in which the means adjacent the upper extent of the sidewalls includes means for classifying the particles as to sizes as well as intercepting material moving up the sidewalls.

7. Apparatus for reducing particle size of material comprising an inner impeller rotatable about a vertical axis, drive means for the impeller adapted to cause rotation to eject material radially outwardly, a hollow outer rotating member having a vertically oriented axis of rotation, an impact region opposite the impeller against which material is ejected, and continuous sidewalls upwardly and outwardly divergent above the impact region, drive means for the hollow outer member to rotate it at sufiicient speed to cause upward movement of particles by centrifugal force along the sidewalls above the impact region, and particle classifying means adjacent the upper extent of the sidewalls above the impeller cooperative with the hollow outer member relative to which the hollow outer member rotates arranged proximate to the walls of said outer member and so constructed and arranged that it selectively mechanically intercepts some of the material moving up the sidewalls and allows only such material that is finer than a predetermined size to flow beyond the upper extent of the outer hollow member.

8. The apparatus of claim 7 in which the particle classifying means comprises a cover member which leaves an annulus between its peripheral edge and the hollow outer member and which is so constructed and arranged that classification proceeds by retaining within the apparatus particles too large to pass through the annulus.

9. The apparatus of claim 8 in which means is provided to enable vertical adjustment of the cover to vary the distance between the sidewalls of the outer hollow member and the peripheral edge of the cover to thereby vary the size of particles which can pass therebetween.

References Cited in the file of this patent UNITED STATES PATENTS 569,828 Herzfeld Oct. 20, 1896 605,302 Trisler June 7, 1898 2,562,560 Marcartney July 31, 1951 2,637,502 Bond May 5, 1953 2,707,314 Horth May 3, 1955 FOREIGN PATENTS 376,760 Great Britain July 5, 1932

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