US2198463A - Mill discharge means - Google Patents

Description

Filed Jan. 26, 1959 2 Sheets-Sheet 1 mlum INVENTOR.

M4170? P. ace/*7,

ATTORNEY.

W. P. SCOTT April 23, 1940.

ATTORNEY.

m r 2 m a mm m E M m om P Gnu Z 2 r mm Q W m 9 w w 6 H w m mm Y C n B h m L w w x 1 m H mm u w I Patented Apr. 23, 1940 UNITED STATES PATENT OFFICE 7 Claims.

This invention relates to the milling of ores and similar material and, more particularly, to the wet grinding and classifying of ores, preferably in the manner known as closed-circuit grinding. Specifically, the invention contemplates the provision of a novel device and a novel arrangement of apparatus elements whereby ground material discharged froma grinding mill, such as a ball mill, pebble mill, rod mill or the like, may be elevated to a point higher than the mill discharge so that it can fiow by gravity to a classifier or other desired destination which may be at an elevation higher than that of the mill discharge, all in a simple, economical and highly eificient manner.

In the milling of ores and other mineral matter it is customary to subject the crushed ore to grinding in a rotating mill containing suitable grinding media such as balls, pebbles or the like, generally together with water or other liquid, whereby the ore is reduced to relatively finely divided condition, thus enabling the valuable constituents to be recovered in subsequent treatment stages. It is also customary to treat the material discharged from the mill in a mechanical or other type of classifier such as a Dorr rake classifier, to separate the finer constituents from the coarser. Where a uniform relatively small size is desired, it is customary to return the coarser material separated by the classifier to the feed inlet of the mill for further grinding and reduction to finer size.

In transferring the mill discharge from the mill to the classifier, or to any other desired destination, it is manifestly preferable for economic and other reasons that the mill discharge be enabled to fiow to its destination by gravity. In many instances this achievement is impossible or impractical, particularly with large size classifiers. because the point at which the feed must be introduced into the classifier is located at an elevation subs .ntially the same or higher than that where the ground material discharges from the mill. In certain instances various means have been utilized to elevate the mill discharge into the classifi r or to a point from where it may fiow by gravity into the classifier or other desired destination. For instance, pumps are sometimes used and compressed air lifts have also been utilized for this purpose. Manifestly any such means requires the trouble and expense of appropriate power for operating the lifting means. I

It is an object of this invention to provide a device, readily attachable to almost any horizontal rotary mill which will operate with the mill and elevate material discharged from the mill to a locality at an elevation higher than that of the mill discharge in a simple, efficient and economical fashion and without necessitating an addi- 5 tional power source.

Another object is to provide a device for closing the circuit between a grinding mill and a classifier which, without requiring additional power or motivating means, will elevate the mill discharge so that it may flow by gravity into the classifier.

With these and other objects in view, the invention consists in the construction and novel combination and arrangement of parts hereinafter fully described, illustrated in the accompanying drawings, and set forth in the claims hereto appended, it being understood that variouschanges in the form, proportion and minor details of construction, within the scope of the claims, may be resorted to without departing from the spirit of the invention or sacrificing any of the advantages thereof.

In the drawings- Fig. 1 is a side elevation of a conventional conical type ball mill having a mill discharge elevating device embodying the features of the present invention attached thereto.

Fig. 2 is an enlarged end elevation,.partly in section, of the elevating device of the invention.

Fig. 3 is a vertical section taken on the line 33 of Fig. 2.

Fig. 4 is an enlarged detail fragmentary view showing the elevating scoops or pockets of the invention.

Generally speaking the invention comprises a wheel or circular member adapted to be attached to the discharge end of a horizontal rotary mill and is provided with pockets which are adapted to receive the material discharged from the mill and, by rotation of the wheel, carry the discharged material to a locality higher than its point of discharge. At substantially the highest point in the circular travel of the pockets the material supported therein, being of a fluid nature, is allowed to discharge from or flow out of the pockets into a suitable launder or other receptacle from whence the material may flow by gravity to any desired destination, in most instances a classifier for separating the material into coarse and fine products.

In Fig. 1 the numeral 5 designates generally a horizontal rotary mill of the conical type and comprises a hollow drum or shell of substantially to be provided at its feed end with a combination scoop feeder l0, new feed entering the feeder at the point H and oversize material returned from the classifier or other separating stage entering the mill by means of the scoop I2 which dips down into a suitable 'tank or hopper, not shown, at each revolution of the mill and scoops up a quantity of the returned material. The drum 5 is provided with a circumferential gear l3 rigidly attached thereto and adapted to engage with a driving pinion, not shown, for the purpose of rotating the entire mill at a suitable speed; It will be understood that the drum 5 contains conventional grinding media such as balls, pebbles,

.rods or the like, which act-upon the material introduced into the mill to disintegrate it into relatively finely divided condition by impact and erosion; The discharge end of the mill will be seen in section in Fig. 3 wherein the shell 5 is seen to terminate in an outwardly projecting annular flange M to which is attached, by a correspondingv annular flange; an internal discharge liner l5 shaped to provide a reduced discharge throat IG-and a somewhat outwardly flared annular discharge lip'l'l.

;It will be understood that the construction so far described is that of a well known type of mill and forms nov part of the present invention.

The mill discharge elevating wheel of the present invention is readily attachable to the shell 5 by co-operation with the annular flange II. The

device preferably comprises a circular disklike member I 8 having a relatively large central opening indicated at I9 and is provided, adjacent the periphery of the opening, with a substantially L-shaped annular flange 20, the vertical or free leg of which is adapted to be attached to the shell 5 by means of bolts 2| passing through the an nular flange I, through the flange on the liner l5 and through appropriate openings in the free leg of the L-shaped flange carried by the member 18. If desired, webs 22 may extend from the disk 18 to the L-shaped flange for the purpose of reinforcing the structure.

Attached, by means of rivets or bolts 23, to the disk member l8 adjacent its periphery and extending circumferentially thereof is a flat strip or backing member 24 which is substantially circular in plan. The member 24 supports a plurality of pockets or scoops 25 which extend outwardly from the backing member substantially at right angles thereto and form pockets for receiving, elevating and discharging material emitted from the mill discharge spout H as will presently be described. In Figs. 3 and 4 the pockets or scoops 25 will be seen to be formed of sheets or strips of metal bent or otherwise shaped into a curved configuration and to have their outer edges somewhat flared outwardly as indicated at 26. Furthermore, a space, indicated at 21, is preferably provided between the outer flared lip of each pocket and the back extremity-of the succeeding pocket. While this is the preferred and configuration that will enable them to receive and hold substantial quantities of fluid or plastic material and, in certain instances, the

openings 2'| 'need not be present, and each pocket 25 be joined to each succeeding pocket, or the exterior periphery of the wheel may be constructed to presenta solid unbroken surface in any other desired fashion. An annular strip or facing member 28 is provided for closing the outer ends of the pockets 25 and is attached to the outer edges of the same in any suitable manner. It will be noted that it is preferred to weld the pockets 25 at each end thereof to the backing member 24 and to the facing strip 28, although it is obvious that any other suitable joining method might be used.

Supported on pedestals 29 is a trough or box 30 which is positioned so that the lower half of the elevating wheel structure extends into it and is completely surrounded and enclosed thereby. The front wall 3| of the trough 30 should extend well upwardly so that it is at least as high the lower part of their rotary movement. Preferably a curved deflecting vane or baflle 32 is provided interiorly of the trough 30 on the front wall 3| thereof to assist in causing the discharged material to gravitate into the lowermost pockets 25 and to prevent, as much as possible, mill discharge from passing between the front wall 3| of the trough and the facing member 28 and accumulating in the trough. As any substantial amount of mill discharge accumulates in the lower part of the trough 30 it will be scooped up by the pockets 25 at the lowermost point of their travel by the outwardly flared edges 26 and through the openings 21. The accumulation of mill discharge in the trough 3|] is therefore reduced to a minimum.

If the mill and elevating wheel were not rotating there would, of course, be a tendency for the fluid mill discharge to run out of the pockets 25, when in their lowermost position, through the openings 21. This tendency'is practically completely overcome, however, by the centrifugal action due to the constant rotation of the elements when in use. With the mill and wheel rotating in the direction of the arrow in Fig. 2, centrifugal action will cause the material discharging from the spout I! to fall slightly to the right of, orat least never to the left of the perpendicular. Thus the discharged material will always fall into the pockets 25 as they start their ascent and never when they are inclined downwardly. Furthermore, centrifugal force, acting upon the contents of the pockets, tends to throw the material away from the openings 21 toward the backs of thepockets so that there is little tendency for it to escape.

While there has been shown a trough 30 completely surrounding the lower part of the elevating wheel, the said trough might, in some instances, be dispensed with. In that event there could be provided an apron or splash plate op-' posite the free side of the wheel and closely adjacent the same and extending upwardly as high as the point of mill discharge. The splash plate, of course, could carry a curved deflector vane or baiile similar to the deflector 32 and for the same purpose. Obviously, any other suitable means could be employed to encourage mill discharge to enter the pockets 25 and to prevent the material from splashing out onto the floor or ground.

An inclined launder is shown iragmentarily at 33, supported in any suitable manner and discharging at its lower end into any suitable ap-1 paratus or receiving means which, in most cases,.

will be a classifier for separating the mill discharge into coarse and fine products. The launder 33 preferably, although not necessarily. parallels a plane at right angles to the axis of the mill and of the elevating wheel of the present invention and is provided at its upper end with alaterally extending receiving section generally indicated at 34. The receiving section 34 extends into the elevating wheel structure so that it is located directly under the pockets 25 as they pass through the higher portion of their rotary travel. As will be seen, the receiving section 34 has a bottom which slants downwardly in one direction toward the main launder 33 and which also inclines generally in a longitudinal direction corresponding substantially to the incline of the launder 33.

In operation, crushed ore or other mineral matter is continuously introduced into the mill through the feed inlet ll along with returned oversize, if desired. introduced through the feed scoop 12, along with water or other desired liquid. The mill 5 is continuously rotated by means of the mill gear l3 cooperating with a driving pinion, and the action of the grinding media reduces the solids to relatively finely divided condition. Incident to the continuous feed of material the ground matter continuously passes out of the mill through the discharge lip 11 in a fluid or plastic condition. It flows in a relatively uninterrupted stream which gravitates into the pockets 25 as they are passing through the lower portion of their rotary travel. It is obvious that the elevating wheel construction will rotate with the mill 5 and as a part thereof, through being rigidly joined to the mill by the bo ts 2|. The mill discharge accumulating in the pockets 25 is carried by the rotation of the same, which rotation is generally in the direction of arrow in Fig. 2, upwardly and circularly until the pockets reach a position substantially adjacent to the end of the launder 33 and its laterally extending section 34. At this point the pockets have assumed a position with respect to the vertical that permits their load of mill discharge to begin to run out of the pockets, and continued rotation of the wheel and of the pockets obviously will permit their entire contents to drain into the laterally extending launder section 34 as the pockets reach the zenith of their travel and begin their downward descent. The trough 30 confines the mill discharge and prevents any of it from splashing or spattering out. The deflector 32, as previously mentioned, assists in directing the stream of discharge into the pockets 25. As any discharged material gets past the deflector and through the openings 21 it will accumulate to a limited extent in the bottom portion of the trough 30. However, the material in the trough will be continuously scooped up by the flared lips 26 and through the openings 21 and thus will not accumulate in the trough to any appreciable extent.

As each pocket, in its rotary travel reaches a position adjacent the end of the laterally ex.- tending launder section 34, its contents will begin to discharge into the launder section and continued rotary travel of the pocket will cause the discharge of its entire contents into the launder section. Due to the lateral and longitudinal inclination of the bottom of the launder section 34 the material discharged thereinto from the moving pockets 25 will flow into the main launder 33 and will thence flow therethrough under the influence of gravity and be discharged from the lower end of the launder into the classifier or whatever is the other desired destination.

Thus it will be seen that there is provided a device which will lift or elevate fluid material discharged from a grinding mill to a locality considerably higher than that of the mill discharge position from whence the material may flow by gravity to a point of ultimate use or disposal. The device is readily attachable to practically any rotary horizontal mill and uses only the rotation of the mill to effect the desired elevation of the mill discharge. Thus no extraneous operating or power means is required to convey the mill discharge to a point of ultimate use which may be at an elevation higher than that of the discharge spout of the mill. The device is simple, rugged and positive in operation and will continuosly lift the mill discharge to an elevated locality in a simple, efilcient and economical fashion.

I claim:

1. For use with a rotary grinding mill having a relatively constricted discharge end portion, a device for elevating material discharged from said discharge end portion to a point above said discharge end portion, comprising a wheel atthe rotation of said wheel and for discharging the material at a high point, a container surrounding at least the lower portion of said wheel, the container wall at the free side of the wheel being provided with a deflector face adapted to direct mill discharge into said pockets across a clearance between said container wall and said wheel.

2. A device according to claim 1, in which each pocket is designed and adapted to scoop up material from said container.

3. A device according to claim 1, in which said deflector face is represented by a semi-circular strip.

4. A device according to claim 1, in which each of said pockets terminates in an outwardly flared lip spaced closely from the back extremity of the next succeeding pocket.

5. A device according to claim 1, with the addition of means for receiving material discharged from said pockets at a location substantially above that of the mill discharge opening, said means comprising a conduit extending at a downward incline and substantially transversely of the axis of rotation of said mill and substantially close to the free side of said wheel, and a discharge receiving portion extending from said chute to intercept the material at said higher point of the wheel.

6. In combination with a rotary grinding mill having a relatively constricted discharge end portion, a device for elevating material discharged from said discharge end portion to a point above said discharge end portion, comprising a wheel attachable to said discharge end portion to be rotatable therewith and having pockets disposed about the periphery of saideral location substantially above that of the mill discharge opening each pocket also being designed and adapted to scoopup material, a container surrounding at least the lower portion of said wheel, which container receives excess material from said mill discharge end, and from which container material is scooped up by said pockets in addition to that received by them from said ,mill discharge and, and conduit means for intercepting the material from said higher peripheral location.

7. A device according to claim 6, in which each of said pockets terminates in an outwardly flared lip spaced closely from the back extremity 6

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