US2999652A - Ore pulverizing mill with centrifugal impact pulverizing action - Google Patents

Description

Sept. 12, 1961 E.'J. DEAR 2,999,652

ORE PULVERIZING MILL WITH CENTRIFUGAL IMPACT PULVERIZING ACTION Filed July 27, 1959 2 Sheets-Sheet 1 IN VEN TOR.

ERV/N cl. DEAR BY j ATTORNEY E.J.DEAR

2 Sheets-Sheet 2 Mg m E r W 7 Id A W V M Sept. 12, 1961 ORE PULVERIZING MILL WITH CENTRIFUGAL IMPACT PULVERIZING ACTION Filed July 27, 1959 u IF i i\aSiiiiizi...iii

2,999,652 ORE PULVERIZING MILL WITH (IENTRIFUGAL IMPACT PULVERIZING ACTION Ervin J. Dear, 495 N. Bowling Green, Los Angeles, Calif. Filed July 27, 1959, Ser. No. 829,863 1 Claim. (Cl. 241-275) This invention relates to ore pulverizing mills and has as its general object to provide an improved pulverizing mill utilizing a centrifugal impact principle of reducing ore in chunk form to a finely pulverized powder.

A primary object of the invention is to provide a pulverizing mill having a pulverizing action of greatly increased elficiency, 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. Specifically, the invention provides a mill which, instead of the 15 to 20 tons daily capacity of prior mills of comparable dimensions, will process from 30 to 35 tons per day, with no extra operating cost. Further, the invention provides a mill which, in a single run of ore chunks therethrough (without rerun) will pulverize the ore to such fineness that 65% of the pulverized material will pass through a 100 mesh screen and 95% will pass a 30 mesh screen.

A further object is to provide an ore pnlverizing mill of maximum simplicity, involving only one moving part,

namely a centrifugal rotor which rotates at high speed upon its driving shaft, and wherein pulverizing, to the extent stated above, is attained in a single pass of ore through the mill.

A further object is to provide an ore pulverizing mill in which pulverizing action is attained almost completely through impact pulverization attained by centrifugal propulsion of the ore chunks from the revolving rotor against a circumferential target, and wherein grinding action is relied on only to a minimum extent.

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 my invention;

FIG. 2 is a vertical sectional view thereof in a median radial plane of the mill;

FIG. 3 is a fragmentary plan view of the rotor periphery as indicated by line 3-3 of FIG. 2;

FIG. 4 is a vertical axial sectional view taken on the line 44 of FIG. 2;

FIG. 5 is a framentary detail sectional view of the housing on an enlarged scale, taken as indicated by line 5-5 of FIG. 2;

FIG. 6 is a fragmentary sectional view of one of the bat units of the rotor, including the parts within the broken line circle 6 of FIG. 2;

FIG. 7 is a fragmentary detail sectional view on an enlarged scale showing the parts indicated within broken circle 7 of FIG. 2; and

FIG. 8 is a detail fragmentary view of the blade liner anchor mechanism.

Referring now to the drawings in detail, I have shown therein, as an example of one form in which my invention may be embodied, a centrifugal impact or crushing mill comprising a base 10 which can be bolted down to a support or may simply rest thereon without attachment thereto; a pair of brace arms 11 rising from the respective ends of base 10; a housing, indicated generally at 12, supported on base 10 and attached to brace arms 11; a rotor 13 rotatably mounted within housing 12; a gasoline engine 14 or other power plant for driving the rotor; and a suitable transmission 15, such as a belt drive, for driving the rotor at a stepped up rate of speed for extremely high speed rotation thereof.

The housing 12 embodies a cylindrical rim 16 which United States Patent 0 material.

Patented Sept. 12, 1961 is of relatively large diameter and narrow axial width, having a pair of integral radial flanges 17 projecting outwardly from its respective front and rear margins, a circular front plate 18 bolted to the forward flange 17, and a circular rear plate 19 welded or otherwise permanently secured to the rear flange 17. These parts are of fairly thick metal, the flanged rim 16 being preferably fabricated from a length of rolled channel section with ends brought together and welded and the forward and back plates 18 and 19 being preferably of boiler plate A series of circumferential spaced bolts 20 are utilized for bolting the front plate 18 to the rim. The upper ends of brace arms 11 are welded to the rim 16 as at 21. The front plate 18 can be demounted from the rim, leaving the rim and the back plate mounted upon the base 10.

Within the rim 16 is a cylindrical liner 22 of tough, hard, wear-resistant material such as manganese steel. The liner 22 functions as a circumferential target against which chunks of ore are thrown at extremely high speed by the rotor 13, with a resultant impact explosion which pulverizes the ore. Secured, as by welding, to the inner face of liner 22 are a series of circumferentially spaced barrier bars 23 extending from the front plate 18 to the rear plate 19 parallel to the axis of rotor 13. Although six of these barrier bars are shown, the number may be increased or decreased somewhat, the bars being spaced circumferentially substantially equidistantly. The function of barrier bars 23 is to change the course of move ment of particles which have acquired substantially a circumferential path of movement and to deflect them inwardly against the periphery of rotor 13.

In the center of forward plate 18 is an inlet 24 to which chunks of ore are fed by a hopper 25 of U-shape, welded to the outer face of forward plate 18. The inlet 24 communicates with a central aperture 26 in front plate 18, Front plate 28 is reinforced around inlet 24 by a flat ring 34 welded to the inner face thereof. Inlet aperture 26 of housing front plate 18 is encircled by a spacer washer 26' secured to its inner face and substantially filling the annular space between front plates 18 and 29 in the inlet area.

A discharge spout 27 is attached to and projects axially from the lower region of front plate 18. It communicates, through the front plate 18, with an annular reducing chamber 35, which is defined between the periphery of rotor 13 and the liner 22. The pulverized material is discharged through the spout 27 by a current of air developed by centrifugal pumping action in the rotor 13.

Rotor 13 comprises front and back end plates 28 and 29 respectively, the latter being secured to a mounting shaft 30- by means of a square flange 31 on the end of the shaft. Shaft 30 extends through a snugly fitting opening in back plate 29, is welded to the edge of the back plate defining this opening, and its inner end is butt-welded to flange 31. Fange 31 in turn is welded to the inner face of back plate 29. The peripheries of end plates 28 and 29 are bridged and joined by a rotor rim 32 to the periphery of which are secured, as by welding, a large number of axially extending impact bars 33 of cylindrical rod section. Radial blades 36 of channel section extend between and are secured, as by welding of their flanges 39, to the inner faces of the front and rear plates 28, 29. The outer end of each blade 36 extends to one side of a respective opening 37 in the rotor rim 32 and is welded to the rim. To each of the blades 36 is secured a blade liner 38 consisting in a flat strip of hard, tough, wear-resistant metal such as T-l manganese steel, having at its inner end a stud 40 which is engaged in a slot 41 in the inner end of a respective blade 36 and is provided with a nut 44 to secure the liner 38 against outward displacement under the high centrifugal loads to which the parts are subjected. Each liner 38 has an apertured car 43 projecting circumferentially rearwardly therefrom and is detachably secured to the rotor by means of an anchor bolt 42 extending through the respective ear 43 and threaded into the rim 32. The outer end of each liner 38 extends through the respective rim opening 37 of the rotor. To remove a worn liner for replacement purposes, the anchor nut 44 is loosened, the anchor bolt 42 is removed, the outer end of the liner is shifted circumferentially away from the respective blade 36 sufficiently to allow the ear 43 to clear the outer end of the blade 36, and the liner is then shifted radially inwardly until the stud 40 on its inner end can be released from the slot 41 in the inner end of the blade 36. After thus releasing the inner end of the liner, the liner is removed radially outwardly through the respective rim aperture 37 and is replaced by a new liner. It will be understood that such servicing operations are performed upon a rotor that has been removed from its housing through the front opening thereof after removing the front plate 18.

To the rim 32, just forwardly of the respective rim apertures 37, are secured to a plurality of bats 45 of extremely tough, hard metal. Each bat 45 preferably has a bolt retainer plate 46 welded to its rear surface and anchoring thereto a pair of threaded studs 47 by means of which the bat 45 is detachably secured to a mounting abutment 48 which is welded to the periphery of rotor rim 32. Nuts 49, cooperating with studs 47, are utilized to bolt the bats 45 to the abutments 48. Thus the bats can readily be detached from the rim of the rotor for replacement when worn out.

The inner ends of rotor blades 36 are spaced radially outwardly from the axis of rotation to define an unobstructed throat space 50 into which ore chunks 51 (FIG. 4) are delivered by hopper 25 to inlet mouth 24.

Operation In the operation of the mill, with the rotor 13 rotating at high sneeds. the ore chunks 51. as they approach the inlet 24, sliding downwardly in the hopper, will be sucked through the inlet by the high suction air current produced by the centrifugal blower action of the rotor. The chunks will tend to follow the spiralling path of air being drawn from the inlet into the segmental spaces between the rotor blades, and as an ore chunk moves outwardly to the radius of the inner ends of the blades, will be picked up by one of the blades and carried along with the blade in the high speed rotation thereof, developing increasing centrifugal force which rapidly impels the ore chunk outwardly in a spirally path with rapidly accelerating speed until finally the ore chunk is thrown at extremely high speed through a respective rotor rim aperture 37 against the target provided by the peripheral liner 22 of the housing. In sliding against the blade liner 38, the ore chunk will have some wearing etfect which increases toward the periphery of the rotor, this wearing efiect ultimately being rectified by replacement of the blade liners. The spiralling paths are indicated by the arrows 51 in FIG. 2. Moving in these spiral paths, some of the fragments will strike the smooth inner surface of peripheral housing liner 22 and others will strike, with direct impact, the internal barrier bars 23, being thereby further disintegrated into smaller particles. By the time the ore fragments have reached this stage of processing, a large percentage of each original ore chunk will have been disintegrated into fine dust through the successive explosive impacts, especially the impact with the housing periphery and its barrier bars 23. Maximum reduction of particle size at this stage of operation is attained through the fact that the original ore chunks have already been fragmentated and the smaller fragments, in moving from the center of the rotor out to the periphery thereof, will have been accelerated to extremely high speeds such that their explosive impact with the barrier bars 23 will result in almost complete disintegration down to powder size particles.

Any ore fragments which are not completely reduced to powder size at this stage of operation will be deflected back into the reducing chamber 35, either by bouncing against the smooth inner surface of peripheral housing liner 22 or by angular deflection against barrier bars 23. In the reducing chamber 35 they will either bounce back cleanly into engagement with the periphery of the rotor 13, or will be struck by circumferentially moving ore fragments in the chamber 35 and thereby impelled either outwardly or inwardly into further impact with the casing periphery liner 22 or the rotor rim. Ultimately all unreduced fragments will be deflected back against the rim of the rotor where they will be picked up by the peripheral driving bars 33 of the rotor or struck by bats 45 and given new impetus of high speed movement in the circumferential direction, causing them to fly off from the rotor rim tangentially and to again strike the housing liner 22 and its barrier bars 23 until finally they are reduced uniformly to powder size.

In the rebounding action of the partially fragmentated ore particles, the bats 45 are particularly elfective in catching the larger fragments, further reducing them directly by impact explosion and imparting renewed momentum to the resulting smaller fragments in the forward direction of particle movement in the reducing chamber 35. The bats 45 are located immediately forwardly of the rotor discharge openings 37, so that minimum interference with the initial discharge of ore fragments from the rotor against the periphery of the housing, will be caused by the bats 45. Thus their action will be concentrated upon the fragments rebounding from the housing periphery liner 22.

A centrifugal blower action is created within the mill by the rotor 13 which will draw air inwardly through inlet 24 into the rotor throat 50 and deliver it to the annular peripheral reducing chamber 35 in which the air, under compression, will rotate in the direction of rotor movement (although not at as rapid a speed). This peripheral rotation of air within the housing will have an effect upon the ore fragments and particles being processed in the chamber 35, of impelling these fragments in the direction of rotor movement so as to assist the particle reduction caused by the high speed impact of the particles against the housing impact bars 23. This impelling effect of the air movement within the chamber 35 will be increasingly effective with decreasing particle size. Thus as the particles become so small that their momentum tends to become ineffective in causing them to rebound within the chamber 35, this decreasing effectiveness of momentum will be offset by the increasing eEectiveness of the air stream in sweeping them along in the chamber 35.

The air which is placed under compression in the chamber 35 will ultimately escape through the outlet 27, carrying with it those particles which have been reduced to the desired powder size and have therefore become so nearly weightless as to follow the air stream rather than to follow their trajectory paths and rebounding movements within the chamber 35. Until they have been thus reduced to powder size, the particles will have too much inertia to be carried by the air stream into the outlet 27. Accordingly, only the finely reduced powdered ore will be delivered through the outlet 27.

The draft of air into the rotor through mouth 24 will be eliective in assisting the movement of ore chunks 51 through the inlet and into the rotor throat 50.

When the liner 22 becomes outworn, the housing can be opened up by removing bolts 20 and front end plate 18, removing the rotor from the housing, removing the worn liner 22 and replacing it with a new liner. In the same manner, blade liners 38 can be removed by first detaching their outer ends by removal of bolts 42 and then releasing their inner ends as hereinbefore described, and new liners can be attached to the blades 36 in replacement for the worn blade liners.

I claim:

An ore processing mill comprising: a housing embodying a circular rim, front and back plates secured to said rim to define a rotor chamber, a cylindrical liner fitted within the rim of said housing, retained by said front and back plates, and having on its inner face a plurality of axially extending barrier bars, said liner and barrier bars being of extremely hard tough, wear resistant material, a rotor mounted in said chamber coaxially and having a rim spaced radially inwardly from the housing rim to define an annular reducing chamber having a radial width roughly equivalent to A the radius of said rim, said rotor comprising a pair of axially spaced cir cular end plates and a cylindrical rim secured to and bridging between the peripheries of said end plates, said rotor rim being provided with a plurality of circumferentially spaced discharge apertures, said rotor further including a plurality of impeller blades secured to the inner faces of and bridging between the respective rotor end plates and having outer ends communicating with the respective rotor periphery apertures at the trailing extremities thereof with respect to rotor rotation, a plurality of removable blade liners of extremely hard, tough wear resistant material each seated against the forward face of their respective blade and detachably secured thereto, the inner ends of said blades and blade liners being spaced radially outwardly from the axis of the rotor to define an unobstructed rotor throat for receiving ore chunks, said rotor having an axial inlet through which such ore chunks can be fed into said throat, and said housing having a hopper and a feed opening communicating with said rotor inlet opening for the feeding or ore chunks into said rotor throat, from which said chunks will be drawn through said feed opening and inlet into said throat and thence into the path of high speed rotation of the rotor blades, will be impelled by said blades in circumferentially and outwardly spiralling paths of movement and discharged through said rotor discharge apertures into said reducing chamber, resulting in explosive impact of the ore fragments against said housing rim liner and against said barrier bars thereof whereby reduction of the ore fragments into small particles will be elfected, said rotor having, on the periphery of its said rim, a plurality of radially projecting bats of hard, tough, wear resistant material adapted to engage with explosive impact, particles rebounding from said housing rim and to impart to them, additonal impetus in their movement within said annular processing chamber, impelling said fragments tangentially into renewed explosive impact with the housing rim and its said barrier bars, and a plurality of axially extending cylindrical impact bars of hard, wearresisting material arranged at substantial uniform circumferential spacing between said bats and not more than 15 angular intervals as subtended at the rotor axis, adapted to engage particles rebounding from said housing rim and to impart to them, additional impetus in their movement within said annular reducing chamber, impelling said fragments tangentially into renewed explosive impact with the housing rim and its said barrier bars, said bats projecting radially outwardly beyond said impact bars, a distance roughly half-way for said rotor rim to the inner surface of said housing liner.

References Cited in the file of this patent UNITED STATES PATENTS 1,772,150 Knowles Aug. 5, 1930 2,192,606 Symons Mar. 5, 1940 2,378,393 Carter June 19, 1945 2,752,098 Adams June 26, 1956 2,798,674 Denning July 9, 1957

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