US3096037A - Ore pulverizer with centrifugal impact action - Google Patents

Description

y 1963 E. J. DEAR ETAE 3,096,037

ORE PULVERIZER WITH CENTRIFUGAL IMPACT AGTION Filed March 5, 1962 2 Sheets-Sheet 1 INVENTORS ERw/v JflEAR By floss/er imp/.55

Arron/5y E. J. DEAR ETAL 3,096,037

ORE PULVERIZER WITH CENTRIFUGAL. IMPACT ACTION 2 Sheets-Sheet 2 July 2, 1963 7 Filed March 5, 1962 INVENTORS Enmv d flEAR y floag'Rr JmPLEs ATTORNEY United States Patent 3,096,037 ORE PULVERIZER WITH CENTRIFUGAL ACT ACTEON Ervin .1. Bear, 495 N. Bowling Green Ave, Los Angeles,

Calif, and Robert W. Staples, 14826 Wyandotte Sh,

Van Nays, Calif.

Filed Mar. 5, 1962, Ser. No. 177,421 8 Claims. (Cl. 241275) This invention relates to ore pulverizing mills of the type having a centrifugal impact type of pulverizing action such as the mill shown in the patent of E. J. Dear No. 2,999,652, issued September 12, 1961. The general object of the present invention is to provide improvements in the mill of that patent.

More specifically, the invention aims to provide a mill having a pulverizing action of greatly improved efficiency, both as to its capacity in terms of volume of ore pulverized per hour, and the fineness with which the ore is reduced to powder form. The invention is adapted to process from 35 to 50 tons per day of ore, reducing the ore chunks in a single run (without a rerun) to a fineness such that 65% of the pulverized material will pass a 100 mesh screen and 95% will pass a 30 mesh screen.

A further object of the invention is to provide a pulverizing mill that will operate with a minimum of loss of the pulverized material into the atmosphere, being sealed against any substantial leakage around this periphery and having an improved centrifugal pumping action in delivering the pulverized tore through its outlet.

A further object is to provide such a pulverizing mill having greatly improved sturdiness and long wear life. This is an especially important attainment of the invention, since in this type of mill, the ore, as it is being pulverized, has an extremely high degree of abrasive action against the pulverizing elements of the mill.

Other objects and advantages will become apparent in the ensuing specification and appended drawing in which:

FIG. 1 is a perspective view of a pulverizing mill embodying our invention;

FIG. 2 is a front elevational view of the same parts being broken away and shown in section to illustrate the internal construction;

FIG. 3 is a detail cross sectional view of one of the centrifugal ejection nozzle and bat assemblies taken on the line 33 of FIG. 2;

FIG. 4 is an axial section of view taken on the line 44 of FIG. 2; and

FIG. 5 is a perspective view of the rear side of the mill.

Referring now to the drawings in detail, we have shown therein as an example of one form in which our invention may be embodied, an ore pulverizing mill comprising, in general, a supporting base A, a housing B, a rotor C rotating within the housing B, and a motor D for driving the rotor C.

Detailed Description Base A comprises a rectangular frame consisting of a pair of side walls connected by cross bars 11 and 12; a middle longitudinal bar 13 welded at its ends to the cross bars 11 and 12; a motor shelf 14 bridging between and secured to one of the side rails 10 and the middle bar 13; a pair of gusset plates 15 each Welded at one end to the forward end of a respective side rail 10 and at its other end to the rim of housing B somewhat below the center thereof; and a pair of brace rods 16 and 17 each welded at its forward end to the back of housing B somewhat above the center thereof and at its rear end to a respective side rail 10, the brace rod 16 being disposed forwardly .of the motor shelf 14 and the brace rod 356961137 Patented July 2, 1963 "ice 17 extending substantially to the rear end of the frame.

Housing B is of shallow cylindrical drum shape, comprising a cylindrical rim 20; a flat circular back wall 21 peripherally welded to the rear margin of rim 20; radial ears 22 integral with or welded to the forward margin rim of rim 20 and projecting outwardly in the plane of said forward margin; and a flat circular front wall 23, detachably secured to the ears 22 by bolts 19. Fitted within the rim 20 is a thick cylindrical target ring 24 having circumferentially spaced, transverse pulverizing teeth 25. Preferably, target ring 24 is of cast steel, extends circumferentially through an arc of approximately 300 degrees and has in a lower right sector thereof, as viewed from the front (FIG. 2) a gap 26 which is bridged by a smooth arcuate liner bar 27.

Flat circular liner rings 28 and 29 are disposed adjacent the wall 21 and front wall 23 respectively, a flat circular gasket 30 being interposed between the front liner ring 29 and the front wall 23. Ring 30 may be of rubber or equivalent plastic material. The peripheral portions of liner rings 28 and 29 are engaged against the flat front and rear faces of target ring 24, which functions as a spacer to maintain the rear liner ring 23 in face to face contact with rear wall 21 and the front liner ring 29 pressed against the gasket 30, which is under compression between the ring 29 and front wall 23.

Between the liner rings 28 and 29, the target ring 24, and the periphery of rotor C, there is defined a pulverizing chamber .31 in which the ore is pulverized against the target ring 24 as it is expelled by centrifugal force from the rotor C.

At the bottom of the housing, the rim 20 is welded to the forward cross member 11 of the base at the center thereof.

In the center .of front wall 23 is an inlet port 32. A hopper, having a downwardly and inwardly sloping front wall 33 and triangular side walls 34 which converge downwardly, is secured to the front wall 23 by welding the lower end of front wall 33 and the rear margins of side walls 34 to the front Wall 23 around the inlet port 32. A front circular collar 35 Welded to the inner face of front wall 23 around port 32, extends the latter toward the center of rotor C.

A discharge nozzle 36, consisting of a short length of cylindrical tubing, is welded to the front wall 23 around a [discharge port 37 therein and projects forwardly, parallel to the rotary axis of the mill. The discharge nozzle 36 is located in communication with the gap 26 in target ring 24, near the end of the sweep of projecting parts of rotor C as they traverse the gap. This arrange ment improves the centrifugal discharge of the pulverized ore as will be explained more fully hereinafter.

Secured to the back wall 21 is a bracket 38, the top of which is horizontal and disposed below a circular aperture 39 in back wall 21, sufficiently to accommodate the radial width of a series of antifrictions bearings 40 and retainer collars 41 in which the bearings are mounted on the bracket 38.

Rotor C embodies centri ugal nozzles comprising tubes 45 of rectangular cross section welded together at their inner ends in the form of a cross, and buttressed by gussets 46 of channel section, triangular in side elevation, and each having a hypotenuse web portion extended and bent back at its apex to provide a seat 47. The triangular side wings 'of the channel section have their right-angular edges fitted into the corners between the four nozzles 45 at the junctions thereof and are welded thereto.

The inner ends of nozzles 45 are in open communication with one another and with an inlet mouth 48 defined by a mouth ring 49 which is welded to the forward Walls of the adjoining inward ends of the nozzles 45. Opposite the mouth ring 49 a circular hub disk 50' is welded to the rear walls of the adjoining inward ends of the nozzles 45 and closes the square space defined between these inward ends. At'their outer ends, nozzles 45 have dis charge mouths 44.

Welded to the center of the hub disk 55 is a shaft 51 which is mounted in the ball-bearings 45, thus supporting the rotor for high speed rotation within the housing B. Secured to the rear end of shaft 51 is a pulley 52 which receives drive from the motor D, transmitted through a driving pulley 53 On the motor shaft and a belt 54 trained around the pulleys 52 and 53.

Secured to the rear Wall of each nozzle 45 is an impeller plate 57 of wedge shape, increasing in thickness from its inner end to its outer end. The chunks of ore entering the rotor through the mouth 48 will be deflected radially outwardly by streams of air which are drawn outwardly through the nozzles 45 (the rotor functioning as a centrifugal pump) will be'engaged by the impeller plates 57, and will slide outwardly against the plates 57 until discharged from the nozzle months 44 at high speed through centrifugal action. The direction of the ore chunks as they slide outwardly against impeller plates 57 is stabilized in radial planes by a series of longitudinal flutes 58 on the inner face of each impeller plate 57.

The inner ends of impeller plates 58 project inwardly past the open inner ends of nozzles 45 into the central area of the impeller, to intercept the ore chunks and guide them into the nozzles 45.

The wedge shape of the impeller plates 57 has two advantages. It provides -a forwardly tilted inclination in the impelling surfaces, increasing the centripetal pressure against the ore chunks tending to retard their passage through the nozzles and correspondingly increasing the centrifugal momentum of the ore chunks as they are released from the outer ends of the nozzles so that they will impact with greater force against the target ring 24, and correspondingly increasing the explosive force of impact against the teeth 25.

The outer ends of impeller plates 57 are abutted against seat bars 59 secured to and traversing the rear walls of the respective nozzles 45 at their outer ends. The seat bars 59 take the centrifugal loads developed in the impeller plates 57 by the high speed rotation of the rotor. Impeller plates 57 are removably secured to the rear walls of the nozzles by studs 60, anchored in the centers of the respective impeller plates, the studs 69 extending through openings in the rear walls of the respective nozzles and being secured by nuts 61, threaded thereon.

The pieces of the ore chunks which are not pulverized at the first impact when thrown from nozzles 4-5, will rebound inwardly into the path of pulverizing bats 65. Bats 65 are positioned against the seats 47 at the apex ends of gussets 46, and are held in place by threaded studs 66, anchored in the respective bats, extending through apertures in the forward walls of nozzles 45, and secured by nuts 67 threaded on the respective studs 66, and reinforcing plates 68, interposed between the nuts '67 and the forward walls of the nozzles. The bats 65 are thick rectangular blocks of hard, tough material such as manganese steel (are also the impeller plates 57).

The forward faces of bats 65 are spaced forwardly from the radial axes of the respective nozzles 45 a distance such that they are tilted rearwardly at an angle of approximately 30 degrees to respective radii intersecting such forward faces. Consequently, as the unpulverized fragments of ore are bounced from the target ring 24 back into the path of the bats 65, they will be struck a glancing blow such as to deflect them outwardly for further impact with the target ring 24.

The outer ends of nozzles 45 are each provided with a pair of fiat wearplates 70 which are welded to the side wall of said outer ends in embracing relation thereto. The plates 70 rotate between the inner portions of liner rings 28 and 29 in closely spaced relation thereto.

Operation In a general way, the operation of our improved mill will be apparent from the foregoing description. One of its improvements in arrangements of parts and operation is the mounting of the bats 65 forwardly of the discharge mouths of the centrifugal nozzles 45. Thus, chunks of ore discharged from one nozzle and rebounding inwardly in the pulverizing chamber 31, will be struck by the bat 65 of a trailing nozzle. We find that a considerable speeding up of pulverization is attained by this arrangement, apparently due to the fact that the elapsed time of discharge of an ore chunk from the end of one nozzle and its rebound back into the path of orbiting movement of the bats 65 will, for a majority of ore chunks, correspond to the elapsed time of movement of the bat of the next railing nozzle up to the vicinity of the rebounding ore fragment.

The gasket 30 seals the periphery of chamber B substantially air-tight so that no pulverized material can seep from the periphery of the housing. This pneumatic sealing of the housing periphery also increases the centrifugal pumping effect and provides an increased volume of air flow through the apparatus.

In the chamber 31, along the length of target ring 24, the circumferential flow of air is disturbed by eddy currents created by the transversely extending teeth 25, such eddy currents improving the pulverizing effect. In the gap 26, there is an undisturbed sweep of the circum ferentially moving air stream which tends to crowd outwardly against the smooth wear plate 27 under the effect of centrifugal force, and where the target ring 24 commences, just beyond the outlet port 37, its projecting end constitutes a barrier to the further circumferential fiow of the air moving in gap 26. The upstream pressure on the body of air moving in gap 26, meeting this increased flow resistance on the downstream side of outlet port 37, creates a maximum discharge pressure in the port 37, resulting in a pressurized stream of airborne ore powder constantly discharged from the mouth of nozzle 36, while the larger fragments of ore that have not been reduced to the predetermined degree of fineness, will sweep pass the outlet port 37, reentering the pulverizing chamber 31 for further pulverization.

The centrifugal nozzles 45 have an aggregate cross sectional area substantially equivalent to the peripheral area of the central chamber of rotor C with which the four nozzles communicate. That is to say, the periphery of this central chamber is substantially wholly open so that there is no restriction to the outward flow of ore chunks entering the chamber through the inlet mouth 43. The streams of ore chunks moving outwardly in the nozzles 45 are wholly enclosed by the four walls of each nozzle and thus are more accurately directed in their tangential paths of discharge from the ends of the nozzles as indicated by arrow 70.

We claim:

1. In an ore pulverizing mill, in combination: a housing comprising a rim, front and back walls secured to said rim in axially-spaced parallel relation, a target ring lining the inner wall of said rim, an inlet in one of said walls at the center thereof, and an outlet in one of said walls, adjacent said rim; and a rotor rotatable within said housing, having an inlet port communicating with said housing inlet and a plurality of peripheral discharge mouths for delivering ore chunks outwardly against said target ring; said target ring being of split ring form, with circumferentially-spaced ends defining a .gap extending circumferentially to said outlet in the direction of rotation of said rotor, from a point spaced from said outlet.

2. In an ore pulverizing mill, in combination: a housing comprising a rim front and back walls secured to said rim in axially-spaced parallel relation, a target ring lining the inner wall of said rim, an inlet in one of said walls at the center thereof, and an outlet in said housing, adjacent said rim; and a rotor rotatable within said housing, having an inlet port communicating with said housing inlet and a plurality of peripheral discharge mouths for delivering ore chunks outwardly against said target ring; said target ring being of split ring form, with circumferentially-spaced ends defining a gap extending circumferentially to said outlet in the direction of rotation of said rotor, from a point between 30 and 60 in advance of said outlet, and means providing a smooth, arcuate wall along the bottom of said gap.

3. In an ore pulverizing mill, in combination: a housing comprising a rim, front and back walls secured to said rim in axially-spaced relation, a target ring lining the inner wall of said rim, an inlet in one of said walls at the center thereof, and an outlet in said housing, adjacent said rim; and a rotor rotatable within said housing, having an inlet port communicating with said housing inlet, a plurality of nozzles of rectangular section tube form, having intercommunicating open inner ends joined to one another and communicating with said inlet port, and in each of said nozzles, an impeller plate attached to the back wall thereof, said plate being of wedge shape longitudinally of the nozzle and converging in relation to the front wall of the nozzle toward the discharge mouth thereof.

4. A mill as defined in claim 5, including a seat integral with and extending circumferentially into said mouth from the outer end of the nozzle back wall, the outer end of said impeller plate being supported against said seat; and a fastener extending through said nozzle back wall, and anchoring an intermediate portion of said impeller plate thereto.

5. In an ore pulverizing mill, in combination: a housing comprising a rim, front and back walls secured to said rim in axially-spaced relation, a target ring lining the inner wall of said rim, an inlet in one of said walls at the center thereof, and an outlet in said housing, adjacent said rim; and a rotor rotatable within said housing, having an inlet port communicating with said housing inlet, a plurality of nozzles of rectangular section tube form, having intercommunicating open inner ends joined to one another and communicating with said inlet port, and, in each nozzle, an impeller plate secured to the inner face of the back wall of the nozzle and extending longitudinally thereof, said plate having a forward face provided with longitudinally extending ribs for guiding ore chunks outwardly in the nozzle in sliding movements thereagainst.

6. In an ore pulverizing mill, in combination: a housing comprising a rim, front and back walls secured to said rim in axially-spaced relation, a target ring lining the inner wall of said rim, an inlet in one of said walls at the center thereof, and an outlet in said housing, adjacent said rim; and a rotor rotatable within said housing, having an inlet port communicating with said housing inlet, a plurality of nozzles of rectangular section tube form, having intercommunicating open inner ends joined to one another and communicating with said inlet port, and, on each nozzle, a disintegrating bat attached to the front nozzle wall on the forward side thereof.

7. In an ore pulverizing mill, in combination: a housing comprising a rim, front and back walls secured to said rim in axially-spaced relation, a target ring lining the inner wall of said rim, an inlet in one of said walls at the center thereof, and an outlet in said housing, adjacent said rim; and a rotor rotatable within said housing, having an inlet port communicating with said housing inlet, a plurality of nozzles of rectangular section tube form, having intercommunicating open inner ends joined to one another and communicating with said inlet port, and, on each nozzle, a disintegrating bat attached to the front nozzle wall on the forward side thereof, said bat being in the form of a thick rectangular block having a back face seated against the forward face of said front wall, and having a front face converging outwardly in relation to a radius of the rotor intersecting its outward extremity.

8. In an ore pulverizing mill, in combination: a housing comprising a rim, front and back walls secured to said rim in axially-spaced relation, a tar-get ring lining the inner wall of said rim, an inlet in one of said walls at the center thereof, and an outlet in said housing, adjacent said rim; and a rotor rotatable within said housing, having an inlet port communicating with said housing inlet, a plurality of nozzles of rectangular section tube form, having intercommunicating open inner ends joined to one another and communicating with said inlet port, and, on each nozzle, 2. disintegrating bat attached to the front nozzle wall on the forward side thereof, said bat having a major portion of its area overlapping and seated against the forward face of said front wall, and having an outer end portion projecting outwardly beyond the outer end of the nozzle.

References Cited in the file of this patent UNITED STATES PATENTS 251,803 Starkey Ian. 3, 1882. 1,499,455 Hadsel July 1, 1924 2,806,496 Waring Sept. 17, 1957 2,920,830 Nyrop et al. Jan. 12, 1960 2,999,652 Dear Sept. 12, 1962

Claims (1)

1. IN AN ORE PULVERZING MILL, IN COMBINATION: A HOUSING COMPRISING A RIM, FRONT AND BACK WALL SECURED TO SAID RIM IN AXIALLY-SPACED PARALLEL RELATION, A TARGET RING LINING THE INNER WALL OF SAID RIM, AN INLET IN ONE OF SAID WALLS AT THE CENTER THEREOF, AND AN OUTLET IN ONE OF SAID WALLS, ADJACENT SAID RIM; AND A ROTOR ROTATABLE WITHIN SAID HOUSING, HAVING AN INLET PORT COMMUNICATING WITH SAID HOUSING INLET AND A PLURALITY OF PERIPHERAL DISCHARGE MOUTHS FOR DELIVERING ORE CHUNKS OUTWARDLY AGAINST AND TARGET RING; SAID TARGET RING BEING OF SPLIT RING FORM, WITH CIRCUMFERENTIALLY-SPACED ENDS DEFINING A GAP EXTENDING CIRCUMFERENTIALLY TO SAID OUTLET IN THE DIRECTION OF ROTATION OF SAID ROTOR, FROM A POINT SPACED FROM SAID OUTLET.

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