US2155150A - Impact crusher - Google Patents

Description

April 18, 1939. w. H. SCHACHT IMPACT CRUSHER 4 Sheets-Sheet 1 Filed Jan. 7, 1953 4 Sheets-Sheet 2 W. H. SCHACHT IMPACT CRUSHER Filed Jan. 7, 1933 April 18, 1939.

4 Sheets-Sheet 3 f W Y m j INIQQ W/ i H w w wfi April 1939- w. H. SCHACHT IMPACT CRUSHER Filed Jan. 7, 1935 4 Sheets-Sheet 4 Zita/12496.}

- in impact crushers.

Patented Apr. 18, 1939 PATENT OFFICE IMPACT CRUSHER William H. Schacht. Painesdale, Mich. Application January 7, 1933, Serial No. 650,597

21 Claims. (Cl. 83-46) My invention relates to a crusher or pulvizer and it has for one object the provision of a machine for reducing rock, ore and the like. Another object is the provision of an improvement Another object is the provision of an associated crushing and screening means for unitary operation. Another object is the provision of an improved crushing and screening installation particularly adaptable for closed circuit crushing. Another object is the provision of means for taking out uncrushable particles, for example native copper, from the closed crushing and screening circuit. Another object is the provision of means for re-feeding oversize to an impact crusher. Other objects will appear from time to time in the course of the specification and claims. l

I illustrate my invention more or less diagrammatically in the accompanying drawings, wherein a Figure 1 illustrates a plan view; Figure 2 is a side elevation; Figure 3 is a front elevation of parts in section on the lineI-lofFlgure 2;

Figure 4 is a section on the line 4-4 of Figure 1;

Figure 5 is a section on the line 8-! of Figure 4;

Figure 6 is a section on the line 6-! of Figure 7;

Figure 7 is a section on the line l--l of Figure 6; 1 I

Figure 8 is a section similar to Figure 7 through a variant'form of the device;

Figure 9 is a vertical section through a variant form of the device similar to Figure 4; and

Figure 10 is.a section on the line Ill-l0 of Figure 9 of a variant form of the device.

Like parts are indicated by like symbols throughout the specification and drawings.

Referring to the drawings, A generally indicates any suitable fixed supporting structure upon which may be mounted any suitable supporting member A held in place for example by the bolts A.

I indicates an impeller spindle to which is secured the impeller structure generally indicated as 2 which includes a disc B and a laterally spaced ring B the ring and disc being connected by a plurality of impeller vanes or struts B which are clearly shown in section as in Figure 5. P0sl-' tioned adjacent and preferably abutting against the impeller vanes B are the impeller striking or wearing plates B of which three are shown in Figures 5 and '7 and only two in Figure 8, it being understood that the number may be varied. The

impeller plate B may include a collar or hub 13 surrounding the end of the impeller shaft l the parts being held against movement as by the bolt B and the nut B and key B". Any suitable means may be employed for rotatably supporting the impeller shaft or spindle I as for example the pedestal and hub bearing bed plate A with its pedestal supports C in which may be mounted the shaft or spindle bearing sleeve 0 held in place as by the clamp members C which may be tightened as by the bolts 0* and nuts (2*. Positioned within the bearing sleeve C are any suitable roller bearings C within the inner race of which is positioned the shaft or spindle I. C indicates a terminal driving pulleyfor the shaft or spindle which may be secured to the end of the spindle l whereby the spindle and the impeller may be rotated. C indicates a main bearing adlusting sleeve within the spindle bearing sleeve C. It will be clear from the figures that whereas the member B is shown as a disc the member B is a ring laterally spaced from and opposite to the periphery of the disc B, whereby, as will later appear, material may be fed for free gravital fall between the disc B and ring B to the wearing plate B. I

Surrounding the impeller structure is the impeller housing structure generally indicated as D. D is the impeller housing bearing which may be mounted in any suitable way on the base A. D? indicates an impeller housing ring bearing hub. D indicates any suitable anti-friction bearing and D is the impeller housing driving sprocket. The housing includes a flat portion D which is outwardly flared as at D and terminates in a species of circular track D which may be supported upon trunnion rollers D rotatable upon adjustable trunnion rollerframes D which may be adjusted as by the screw device D upon the trunnion roller base D The interior. of the impeller housing is provided with any suitable ,liner plates D as shown in Figure 4.

. ure 4 the striker plates lie in the plane of rotation of the impeller wearing plates B and any material which passes between the impeller plates or which is driven from the impeller plates by the crushing or disintegrating impact, is received by the striking plates. As will later appear, the rate of feed and the rate of rotation is such that material cannot drop through the path of movement of the striking plates without receiving a crushing or disintegrating impact, the action of which is indicated for example in Figures 4 and 5.

Further secured to the impeller housing structure is a circumferential grizzly or screen generally indicated as G. It may be bolted or otherwise suitably secured to the outer edge of the impeller housing as at G and is provided with a forward circumferential side ring G Associated with the rotating grizzly structure are a plurality of elevator buckets Ci which therefore rotate unitarily with the impeller housing. Any material which falls to pass through the grizzly or screen is picked up by the buckets and upwardly conveyed until aligned with and discharged upon the surfaces of the oversize return chutes G The main line of feed is along the feed chute G and the oversize chutes G return the oversize picked up by the buckets G to .the main line of feed along the chute G The result is a closed crushing and screening circuit, the only normal escape from the circuit being through the screen.

However, it may happen, as in screening copper ore, that uncrushable masses of native copper may accumulate in the circuit. Similarly, uncrushable masses may accumulate in the crushing and screening of other materials. In order to permit the removal of such material I provide a rejector chute generally indicated as H which may be pivoted as at H and which may be moved inwardly into the line of feed or delivery along the chute G whereby the feed, or oversize, may be temporarily by-passed to the picking deck H", for the removal of the undesired particles. Whereas I have shown a single pair of links H it will be realized that I may employ additional links if desirable. The deck IF may be pivoted as at H whereby it may be dropped into the dotted line positiori as at 1-1, after the picking has been completed. B indicates a picking deck return chute, which delivers the particles on the deck back into the crushing and screening circuit. As it is possible that some particles may bound or rebound within the circle. defined by the impeller surfaces 13 forming a spiral of material which is not being properly disintegrated, I provide a fixed or stationary striking plate J, shown for example in Figure 5, which is located under the upper portion of the inner circle formed by the path of the revolving impeller plates B and which is preferably at right angles to the plane of the impeller, and which therefore intercepts the swirl of stray material swept around by the impeller, that has not succeeded in passing through the circular path of the impeller striking plates B This material is deflected, by the aid of gravity, with sufficient velocity into the path of the impeller plates, to rejoin the general crushing or disintegrating cycle. The plate J may also have a certain further disintegrating effect on such strayf material as contacted. The rotary motion will be stopped and the material will fall vertically or nearly so, into the path of the impeller plates, with the aid of gravity and with the aid of the air velocity caused by the fan action of the impeller, which tends to suck or drive air radially outwardly away from the center of the impeller structure.

K indicates a hinged shield for closing the forward face of the machine. It is hinged for example by the hinges K which in turn are secured to the supporting posts K rotatable in any suitable bearings K one hinged half of the shield K is omitted from Figure 3 in order to show the interior of the device. In the machine as employed, two hinged shields are employed each mounted on a post K the post being situated on opposite sides of the front of the machine. Feed chutes are attached to one half of the shield only, so that inspection can be made without disturbing the chutes. It

will be understood that by swinging the shields aside the entire interior of the structure is exposed to view, which is a help in inspection. K indicates any suitable outer shell or housing It will be understood that about the grizzly, which may be open at the bottom as at K to discharge material passing through the grizzly or screen. It is indicated as having inclined lower sides K which may be used to serve as limiting chutes.

Referring to Figure 1, I preferably employ a plurality of motors. I illustrate for example a primary motor 0 for the impeller, which is provided with a pulley O slotted to receive a plurality of belts O which serve to drive the pulley C of the impeller shaft. A secondary motor 0 through any suitable gear reducer O maydrive the sprocket O and thereby the chain 0 passing about the sprocket D of the impeller housing. -I illustrate in Figures 9 and 10 a variant form in which I employ two impellers, a primary im-.

peller and a secondary impeller. These impellers are driven at a rapid rate of speed and in opposite directions of rotation. Referring to these drawings, M indicates the primary impeller spindle with its drive pulley M its impeller disc M impeller ring M struts M and wearing or impact plates or faces M N indicates a driving sleeve for the secondary impeller, with its drive pulley N secondary impeller disc N secondary impeller ring N connecting struts N and impact members N Since the remaining parts of the device have the same function as in the other forms I will not describe or show the parts in detail.

It will be realized that whereas I have described and shown a practical and operative device, nevertheless many changes might be made in the size, shape, number and disposition of parts without departing from the spirit of my invention. I therefore wish my description and drawings to be taken as in a broad sense illustrative and diagrammatic rather than as limiting me to my specific showing.

The use and operation of my invention are as follows:

Broadly stated, my method and apparatus are for the purpose of reducing the size of ore, rock or other material, by disintegrating it by a series of impacts with the striking or wearing plates B which are fixed radially, or nearly so, to the vanes or cross braces of the impeller. The impeller includes the circular disc B which is mounted centrally at the end of the spindle I. The impeller and the impeller housing structure generally indicated as D rotate about a common axis, but are separately rotated and preferably at greatly different speeds. Material may be fed down by the main feed chute G and is thereby delivered into the space between the plate or disc B and the ring B of the impeller. The material falls by gravity and preferably the chute is of sufficient length or the height of' initial feed is sufiicient to impart a very substantial gravity acceleration.

Furthermore, the vanes of the impeller have a fan effect which tends to discharge air radially outwardly from the inner space of the impeller and this air movement further speeds the falling particles after they pass below the axis of rotation of the impeller. Therefore the material to be reduced is fed at a high rate of speedthrough the open end of the impeller on its downwardpath from the feed chute and,-as it passes between the disc 3 and the ring B into the line of movement of the striking plates B each particle receives a disintegrating impact. The impeller'revolves at a high rate of speed about its horizontal axis, at such a rate that in order to intercept an impact of all or more substantially all of the falling particles one, two or three or more of the members B may be necessary. The feed chute G may be steeply inclined, at an angle of degrees more or less. The falling particles attain suflicient velocity relative to the velocity of the impeller striking plates B to reach the path of the impeller plates before they are struck and the rates of rotation and the length of fall are preferably so timed and arranged that the particles make a full and complete contact with the faces of the striking plates B rather than merely being struck by the top edges only.

The members B serve as reinforcing vanes and struts. In order to prevent vibration or centrifugal strain caused by the rotation of an unbalanced member I provide balancing washers 3 which may be threaded upon the balancing assembly pin B their displacement being prevented by any suitable nut B".

In the form of Figures 5 and 7 I illustrate the employment of three of the impact members B one for each of the struts. In Figure 8, where I wish to employ but two of the members B I illustrate four of the struts 13 arranged in pairs. Two of the struts extend all the way in to the inner edges of the members B The other struts do not extend so far in and the impeller is preferably driven at such a rate that each impact member or plate B prevents the contact of the falling particles with the following strut. That is to say, the following strut is positioned radially outwardly a sufllcient distance so that any falling particle which could meet it is contacted by the preceding member B The particles which clear one of the members 13 have not moved far enough when the following strut comes in line to be hit by it, but will be hit by the following plate 13 In other words, if the velocity of the feed is that of the impeller, then the secondary strut must be set farther from the center of the impeller than the striking plate strut by a distance equal to itsdistance from the striking plate strut, in order not to interfere with the feed. For the reduction of fine sized feed of ore, rock, etc., four or more impeller striking plates may be employed.

The annular ring B serves not only to support the ends of the struts but has the secondary function of confining and directing the passage of the broken ore or rock and also to create a definite air circulation through the impeller, to help carry the material or particles therethrough.

The reflector ring E with the plates E surrounds and is concentric with the impeller, revolving about the same axis. After impact with the impeller striking plates B the broken or partly disintegrated material instantly attains a high velocity, due to centrifugal force acting on it by the rotating impeller, and is thrown out- Wardly from the impeller and downwardly and to the return chute H outwardly against the wearing plates E of the reflector ring. Centrifugal force, combined with the force of gravity and the force of the air current set up by the impeller, all act on thematerial in the same general downward direction, giving it ahigh velocity which directs the particles against the wearing plates E, resulting in a secondary reduction of the material.

There is some further reduction of particles of ore or rock caused by their striking each other in passing from the impeller to the reflector ring plates and vice versa. There is also some further reduction caused by particles bounding or rebounding from the reflector ,plates and again getting into the path'of the revolving impeller striking plates. The stationary striking plate J also has some disintegrating eiiect although its primary purpose is to intercept the swirl of stray material swept around by the impeller, that has i not succeeded in passing through the circular path of the impeller striking plates. This stray material is directed back into the path of the plates B.

For screening the disintegrated product I provide a circumferential screen or grizzly which rotates in unison with the impeller housing. The particles which are sufficiently reduced will pass through the screen or grizzly to any suitable conveying means. The oversize particles which cannot pass through the grizzly are picked up by the buckets G and are thereby returned to the over-. size return chutes G and thus to the feed chute G As the result is a closed screening and disintegrating circuit, any non-reducible material should be removed from the circuit. For removing such material, such as tramp iron, steel, or native copper, or the like I may intercept the flow of the oversize return feed by the chute H,

without shutting down the machine. intercepts the oversize return and directs it to the picking table H. The uncrushable material is there picked and removed and the residue may be returned by tilting the table H to deliver it This ready means of removing uncrushable material makes unnecessary the use of a magnetic pulley for the removal of tramp iron or steel. Such foreign material can It simply enter the machine without causing injury, be-

cause the clearance between the impeller and reflecting ring plates is several times the opening of other crushers making a product the same size. In other words, all that such uncrushable particles will do is to travel around the closed circuit without being disintegrated or screened. When there is s'ufllcient' accumulation of such particles to make it worth /while, the rejector chute H is simply moved into position and such particles will then be delivered to the picking table IP for removal by picking. The construction of the machine permits partial or entire removal of the impeller, with its spindle shaft I, bearing sleeve and driving pulley C", to facilitate replacement of the striking plates of the impeller and the reflecting ring wearing plates, without further dismantling the machine. This may be done by simply sliding the impeller spindle or shaft sleeve with the shaft and impeller in place through the impeller housing ring beartightens and holds the wedge-shaped striking plates 13 in place. To change the plates it is necessary to tap them attheir outer edge to loosen them.

A stationary or non-rotated hinged shield K is provided for closing the open end of the revolving impeller housing, and for supporting the feed and discharge chutes. The hinged chute is formed of two parts or halves, the feed or dis-' charge chutes being mounted upon one half only thereof.

The control of the intensity of the impact forces is a matter of importance. For a given diameter of impeller and a given speed, the in-' tensity with which the partly reduced material is thrown out against the reflector ring, wear plates or the secondary impeller striking plates, by the impeller is controlled by the variation of the angle between a radial line drawn through the center of the impeller and some point on the plane of the face of the impeller striking plate. The intensity may therefore be varied by merely changing the angle of the faces of the members B opposed to the material. The same effect is obtained by varying the faces M or N ofthe variant form. The intensity may also be controlled by varying the speed of the impeller and by varying the diameter of the impeller. The combination of these varying factors makes possible a control of the breaking force to suit the requirements for braking ores or rock of different hardness or size in order to get the greatest amount of work out of a givenpower input.

Referring to the form of l lgures 9 and 10, I illustrate a device having a primary and a secondary impeller which are separately driven and are rotated in opposite directions of rotation. The action of the machine with this modification is identical with the action of the form. of Figures 1 and following, except that the ore or other material, instead of being directly thrown from the striking plates 13 of the primary im-- peller against the reflector ring plates after the primary reduction, are thrown against the striking.plates of the secondary impeller which revolve in an opposite direction. The impact with the striking plates of the secondary impeller makes the secondary reduction. After this secondary reduction, the broken ore or rock is' thrown against the reflector ring wear plates, E and the process continues as previously described.

Ample clearance space is provided between the inner circular path of the striking plates of the secondary impeller and the outer circular path described by the striking plates of the primary impeller, so as to pass any non-reducible foreign material without injury to the impellers. The secondary impeller is shown as having several times as many striking plates as the primary impeller, and it may be revolved at the same speed or at a lower or higher speed than the primary impeller. The extent of the secondary reduction may be controlled by varying the speed of the secondary impeller, or by varying the angle that the face of the impeller striking plate makes with a radial line drawn through it.

In defining the operation of my device I may employ the term inner path as the inner margin or inner face of the path described by the impact members as they run in their normal operation, the cylindrical surface defined by that part of the impeller members nearest their center of rotation. The outer path is the corresponding cylinder defined by the parts of the impellers farthest from their center of rotation. While I say cylindrical for purpose of illustration, it will be understood that I do not wish to be limited to any particular figure or shape, as the path might be conical or otherwise shaped.

I claim:

1. In an impact crusher, an impeller, a reflecting ring surrounding said impeller, and means for rotating said impeller and said reflecting ring concentrically about a generally horizontal axis, one or more impact members mounted upon and rotating with said impeller, means for feeding material by gravity into the space defined by the path of said impact members, and for causing it to fall freely by gravity through the inner path of the impact members, into the line of movement of the impact members, and rotary screening means for receiving the particles discharged from said impact members and reflector ring, means for re-feeding to said impact members the particles which fail to pass through the screening means, 'means for withdrawing particles from the feeding circuit so formed, including a reiector chute, and means for moving it into the line of feed.

2. In an impact crusher, an impeller, a reflecting ring surrounding said impeller, and means for rotating said impeller and said reflecting ring concentrically about a generally horizontal axis,

- one or more impact members mounted upon and rotating with said impeller, means for feeding material by gravity into the space deflned by the path of said impact members, and for causing it to fall freely by gravity through the inner path. of the impact members, into the line of movement of, the impact members, and rotary screening means for receiving the particles discharged from said impact members and reflector ring, means for re-feeding to said impact members the particles which fail to'pass through the screening means, means for withdrawing particles from the feeding circuit so formed, including a rejector chute, and means for moving it into the line of feed, a picking deck to which said rejector chute delivers and a return chute adapted toreceive material from said picking deck and to return it to the crusher.

3. In an impact crusher, an impeller, a reflecting ring surrounding said impeller, and means for rotating said impeller and said reflecting ring concentrically about a generally horizontal axis, one or more impact members mounted upon and rotating with said impeller, means for feeding material by gravity into the space defined by thepath of said impact members, and for causing it to fall freely by gravity through the inner path of the impact members, into the line of movement of the impact. members, and rotary screening means for receiving the particles discharged from said impact members and reflector ring, and means for re-feeding to said impact members the particles which fail to pass through the screening means, including elevator buckets mounted for movement with said rotary screening means and a feed chute adapted to receive the material discharged by said buckets.

4. man impact crusher an impeller rotatable about a generally horizontal axis. and means for rotating it, a pluraliiy of impact members mounted upon said impeller, said impact members being spaced radially from the axis of said impeller and being spaced circumferentially about said impeller, means for directing material into the space defined by the path of the impact mem-' bers, said impact members being provided with impact faces adapted to engage the particles falling. therebetween, a reflector ring surrounding the impeller and lying in the general plane of the impact members and adapted to receive particles centrifugally delivered by the impact members, said reflector ring having a free edge, whereby the crushed partcles can escape readily beyond said reflector ring after crushing, a rotary grizzly adjacent said reflector ring, means for directing crushed material from said reflector ring to the rotary grizzly, and means for rotating said reflector ring and rotary grizzly in unison.

5. In an impact crusher an impeller rotatable about a generally horizontal axis, and means for rotating it, a plurality of impact members mounted upon said impeller, said impact members being spaced radially from the axis of said impeller and being spaced circumferentially about said impeller, means for directing material into the space defined by the path of the impact members, said impact members being provided with impact faces adapted to engage the particles falling therebetween, a reflector ring surrounding the impeller and lying in the general plane of the impact members and adapted to receive particles centrlfugally delivered by the impact members, said reflector ring having a free edge, whereby the crushed particles can escape readily beyond said reflector ring after crushing, a rotary grizzly adjacent said reflector ring, means for directing crushed material from said reflector ring to the rotary grizzly, and means for rotating said reflector ring and rotary grizzly in unison about an axis generally concentric with the axis of rotation of the impeller. Y I

6. In an impact crusher an impeller rotatable about a generally horizontal axis, and means for rotating it, a plurality of impact members mounted upon said imp'eller, said impact members being spaced radially from the axis of said impeller and Ming spaced circumferentially about said impeller, means for directing material into the space defined by the path of the impact members, said impact members being provided with impact faces adapted to engage the particles falling therebetween, a reflector ring surrounding the impeller and lying in the general plane of the impact members and adapted to receive particles centrifugally delivered by the impact members, said reflector ring having a free edge, whereby the crushed particles can escape readily beyond said reflector ring 'after crushing, a rotary grizzly adjacent the reflector ring, and a guide ring adapted to receive the material discharged from the reflector ring and direct it to the rotary grizzly.

7. In an impact crusher an impeller rotatable about a generally horizontal axis, and means for rotating it, a plurality of impact members mounted upon said impeller, said impact members being spaced radially from the axis of said impeller and being spaced circumferentially about said impeller, means for directing material into the space deflned by the path of the impact members, said impact members being provided with impact faces adapted to engage the particles falling therebetween, a reflector ring surrounding the impeller and lying in the general plane of the impact members and adapted to receive particles centrifugally delivered by the impact members, said reflector ring having a free edge, whereby the crushed particles can escape readily beyond said reflector ring after crushing, a rotary grizzly adjacent the reflector ring, a guide ring adapted to receive the material discharged from the reflector ringand direct it to the rotary grizzly, and means for unitarily rotating the guide ring, reflector ring and grizzly about an axis generally concentric with the axis of rotation of the impeller.

8. In an impact crusher a rotary impeller mounted for rotation about a generally horizontal axis and means for rotating it, and a unitary rotatable housing member surrounding said impeller and rotatable about a generally concentric axis, and independent means for rotating it, a reflector ring mounted on said housing in the same general plane as the plane of rotation of the impeller member, a rotary grizzly mounted upon and rotatable with said rotary housing, and movable means for closing the forward face of the rotatable housing.

9. In an impact crusher a rotary impeller mounted for rotation about a generally horizontal axis and means for rotating it, and a unitary rotatable housing member surrounding said impeller and rotatable about a generally concentric axis, and means for rotating it, a reflector ring mounted on said housing in the same general plane as the plane of rotation of the impeller, a

rotary grizzly mounted upon and rotatable with said rotary housing, and movable means for closing the forwardiace of the rotatable housing, including a fixed housing and a closure therefor.

10. In an impact crusher, a rotary impeller mounted for rotation about a generally horizontal axis and means for rotating it, a reflector ring mounted for rotation in the same general plane as the plane of rotation of the impeller said impeller including impact members adapted to direct impacted particles centrifugally against the reflector ring for a second crushing impact, and a rotary grizzly mounted for rotation in unison with said ring, and means for directing particles from the reflector ring to the rotary grizzly, the reflector ring having a free edge, whereby the crushed particles can escape readily from the ring after crushing.

11. In an impact crusher, a rotary impeller mounted for rotation about a generally horizontal axis and means for rotating it, a reflector ring mounted for rotation in the same general plane as the plane of rotation of the impeller, a rotary grizzly mounted for rotation in unison with said ring, a chute adapted to deliver material through the plane of said grizzly and directly into the space deflned by the path of movement of the impeller, and means associated with the grizzly, for delivering into said chute the oversize material for recrushing.

12. In an impact crusher, a rotary impeller mounted for rotation about a generally horizontal axis and means for rotating it, a reflector ring mounted for rotation in the same general plane as the plane of rotation of the impeller, a rotary grizzly mounted for rotation in unison with said ring, and a guiding ring adapted to direct the crushed material which escapes from the reflector ring to the rotary grizzly.

13. In an impact crusher, a rotary impeller mounted for rotation about a generally horizontal axis, said impeller including a shaft and a plate mounted at one end thereof, impact members associated with said plate, a reflector ring surrounding said impeller and lying in the general vertical plane of the impact members, means for supporting and rotating said ring including an open rotary housing surrounding said ring and extending to the rear of the impeller plate, and guiding means associated with said housing and extending closely adjacent to the periphery of the plate, adapted to prevent the penetration of material to the rear of said plate.

14. In a two-stage impact crusher, means for imparting a primary crushing impact to freely falling particles, which includes a single rotatableimpeller, a plurality of primary impact members normally fixed upon said impeller, spaced radially from the axis of the impeller, and spaced circumferentially about the impeller, and means for gravitally projecting an unconsolidated stream of particles along a defined and unobstructed path, into the path of movement of the impact members of the impeller at a velocity sufficient to carry substantially each particle of the stream fully into said path, whereby substantially each particle is positioned to be squarely impacted by the impact face of the impact members of the impeller, means for rotating said impeller at such speed and momentum as will cause adequate crushing impacts, and at the time of such impacts will present the faces of its primary impact,

members to squarely impact the particles which penetrate into the path of the primary impact members, and means for imparting a secondary crushing impact to the particles crushed by the primary impact, while said particles are in flight from the impeller and its impact members, including an imperforate breaker member 'positioned radially outwardly from the impeller at a distance from the periphery of the impeller substantially greater than the diameter of the maximum size 01' particles being crushed, and lying in the plane of the primary impact members, and adapted to receive the particles centrifugally delivered by the primary impact members thereagainst, said breaker member having a free edge and being adapted to permit the ready gravital removal from the face thereof of the particles impacted thereagainst.

15. The structure of claim 14 characterized by the employment, as a breaker member, of an imperi'orate member surrounding the impeller and lying in the general plane of the impeller and adapted directly to receive all the particles centrifugally delivered by the impeller, said breaker ring having a free edge whereby the crushed particles can escape readily from the edge of the ring after crushing.

16. The structure of claim 14 characterized by the employment, as a breaker member, of a continuous-ring surrounding the. impeller and lying in the general plane of the impeller and adapted directly to receive all the particles centrifugally delivered by the impeller, said breaker ring having a free edge whereby the crushed particles can escape readily from the edge of the ring after crushing, and a combined rotary grizzly and elevator, and means for rotating it about an axis generally concentric with the 'axis of rotation of the impeller, and means for returning over-size particles from said grizzly and elevator into the line of projection, whereby such oversize particles re-enter the path of movement of the primary impact members.

17. The structure of claim 14 characterized by the employment, as a breaker means, of a continuous ring surrounding the impeller and lying in the general plane of the impeller and adapted directly to receive all the particles centrifugally delivered by the impeller, said breaker ring having a free edge whereby the crushed particles can escape readily from the edge of the ring after crushing, and a combined rotary grizzly and elevator, and means for rotating it about an axis generally concentric with the axis of rotation of the impeller, and means for returning over-size particles from said grizzly and elevator into the line projection, whereby such oversize particles re-enter the path of movement of the primary impact members, and means for rejecting uncrushable material from the return circuit thus provided.

18. In an impact crusher, a rotary impeller mounted for rotation about a generally horizontal axis, and a rotary combined grizzly and elevator mounted for rotation about a generally concentric horizontal axis, said grizzly and elevator being axially spaced along the common axis, and lying in a vertical plane at one side of the impeller, and a breaker ring surrounding said impeller and lying in the plane of said impeller but rotating in unison with and coaxial with the combined grizzly and elevator, means for delivering material from the plane of the breaker ring to the plane of the combined grizzly and elevator, the breaker ring having a free edge adapted for the ready gravital escape of material therefrom, and a feed chute adapted for the unobstructed guiding and delivery of an unconsolidated stream of material at high velocity to the rotary impeller through the path of its impact portions, the upper end of said chute being positioned at a level substantially higherthan the uppermost portion of the impeller, said chute inclining steeply downwardly through the open interior of the combined grizzly and elevator and terminating at a point adjacent the vertical plane defined by the edge of the impellerclosest to the grizzly and elevator.

19. The structure of claim 14 characterized by the employment, as a gravital projecting means, of a chute adapted to direct a stream of the particles to be crushed into the space defined by the inner edges of the impact members, whereby said particles are directed downwardly and without obstruction into the path or said impact members through the circular path defined by said inner edges.

20. In an impact crusher, a pair of concentric rotatable impellers and means for rotating them about their concentric axes in opposite rotational directions, each said impeller including a plurality of impact members spaced radially from the axis of the impeller, and spaced circumferentially about the impeller, the impact members of the two impellers being spaced by different radial distances from their common center of rotation, and means for gravitally directing an unconsolidated deflned stream of material into the path of movement of the impact members of the inner impeller, at a velocity sufficient to carry substantially each particle of the stream fully into said path, whereby substantially each particle is positioned to be squarely impacted by the impact face 0! the impact members of the impeller, the spaces between the impact members of the inner impeller being of 'sufllcient peripheral extension to permit the impacted particles to be delivered centrifugally outwardly therethrough and into the path of the impact members of the outer impeller, and imperforate breaker means positioned radially outwardly from the outer impeller, at a distance from the periphery of said impeller substantially greater than the diameter of the maximum size of particles delivered outwardly from said impeller, and lying in the plane of the impact members, and adapted to receive the particles centrifugally delivered by the primary impact members thereagainst, said imperforate breaker member having a free edge.

21. In a two-stage impact crusher, means for imparting a primary crushing impact to freely failing particles, which includes a single rotatable impeller. a plurality of primary impact members normally radially maintained when in opera-' tive position upon said impeller. spaced radially from the axis of the impeller, and spaced circumierentially about the impeller, and means for gravitally projecting an unconsolidated stream of particles along a defined and unobstructed path, into the path of movement of the impact members of the impeller at a velocity suilicient to carry substantially each particle oi the stream fully into said path, whereby substantially each particle is positioned to be squarely impacted by the impact face of the impact members of the impeller, means for rotating said impeller at such speed and momentum as will cause adequate crushing impacts, and at the time of such impacts will present the faces of its primary impact members to squarely impact the particles which penetrate into the path of the primary impact members, and means for imparting a secondary crushing impact to the particles crushed by the primary impact, while said particles are in flight from the impeller and its impact members, including an' imperforate breaker member positioned radially outwardly from the impeller at a distance from the periphery of the impeller substantially greater than the diameter of the maximum size of particles being crushed, and lying in the plane of the primary impact members, and adapted to receive the particles centrifugally delivered by the primary impact members thereagainst, said breaker member having a free edge and being adapted to permit the ready gravital removal from the face thereof of the particles impacted thereagainst.

WILLIAM H. SCHACHT.

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