US1450289A - Apparatus for entraining and removing fines from conical milis - Google Patents

Description

Apr.3,1923.

H. W. HARDlNGE APPARATUS FOR ENTRAINING AND REMOVING FINES FROM CONICAL MILLS Fil ed Apr. 29, 1920 INVENTOR %& ATTORNEYS Patented Apr. 3, 1923.

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HARRY W. HARDINGE, OF NEW YORK, N. Y.

APPARATUS FOR ENTRAINING AN'D REMOVING FINES FROM CONICAL MILLS.

Application filed April 29, 1920. Serial No. 377,489.

To all whom it may concern Be it known that I, HARRY W. HARDINGE, a citizen of the United States, residing at New York, county and State of New York, have'invented certain new and useful Improvements in Apparatus for Entraining and Removing Fines from Conical Mills, of which the following is a full, clear, and exact description.

This invention relates to a process of and apparatus for grinding or disentegrating cement, coal, ores or other materials.

I Conical mills are now well known in the art (see for example, among other patents, my U. S. Patent No. 908,861) and may be somewhat generally described as follows. Such mills comprise a drum having an inlet opening or openings, a conical outlet ortion and an outlet opemng or openings. he

conical outlet portion performs important functions. It is by virtue of this portion that the material is automatically classified according to size by the rotation of the mill. In this classification the coarser material lies toward or adjacent the inlet of the mill and the particles of material diminish in size toward the apex of the cone shaped portion. In other words, because of the inherent classifying action of the mill the fines travel automatically toward the apex of the cone leaving the coarser particles behind until they are reduced to thedesired degree of fineness.

One of the principal objects of the present invention is to provide a method of and apparatus for aiding the above described inherent classifying action of conical mills. Stated somewhat generically the invention comprises employing the conical outlet or a portion thereof as a conduit through which a current of elastic fluid is directed toward the outlet opening from the inside of the drum. Numerous important functions flow from this feature as will hereinafter appear. The method or process may perhaps best be described by more or less detailed consideration of some of the forms of apparatus by which it may be carried out.

eferri'ng to the drawings which illustrate what I now consider preferred physical embodiments of my invention:

Fig. 1 is a somewhat diagrammatic view illustrating one form of my invention.

Fig. 2 is a similar view illustrating a modification.

Calling attention to Fig. 1 the conical mill there illustrated comprises a drum 1 rotatably mounted; in bearings 5, 6 and which may be rotatedabout its longitudinal axis by any suitable means (not shown). The drum 1 is provided with ing 3 through which'material to be ground may be fed and an outlet opening 4 through which the ground material is discharged. By virtue of the conical outlet portion 2 rotation of the drum not only causes disintegration of the material but the material is automatically classified according to size as above described and as indicated more or less diagrammatically in Fig. 1. It is important, for various reasons, that the material be removed from the drum with the utmost despatch so soon as it is reduced to the desired degree of fineness. Some of the more important of these reasons may be stated as follows. Any fines Within the mill are so much dead weight and'increase the power required to rotate the mill. Fines withinthe mill also serve as a cushion and the larger particles of material do not receive the full disintegration-causing impact during the rotation of the mill. The problem of removing the fines as soon as possible after they are formed (or in other words aiding the inherent classifying action of the mill) is rendered somewhat difficult dueto the fact that the amount of fines increases towards the apex of the cone 2.

In accordance with my invention I cause a current of elastic motive fluid to enter the drum through a suitable inlet opening or openings which current then flows through the conical outlet toward the apex thereof and out through an outlet 0 ening or openings. One way of effecting t is result is illustrated in Fig. 1. The outlet opening 4 of the mill is employed as the outlet opening for the fluid stream and the flow or current is created by creating a negative pressure or suction at said outlet 4 by any suitable means. One form of such means is illustrated in the last mentioned figure and may be constructed as follows.

an inlet openhe outlet 4 communicates with a stationary conduit or passage 7 provided with a converging portion 8 and a motive fluid inlet 11 terminating in a nozzle 10. It will be appreciated that the elements 10, 11 and 8 constitute an ejector and .by introducing motive fluid such as gas or liquid or mixture of the same under pressure through the nozzle 10, a negative pressure or suction will be created at the opening 4. As the opening 3 is Wholly or partially open to atmosphere a stream of air will enter the through the conical outlet indicated in the drawtrained in the current and carried with it through the outlet 4. Furthermore those of the fines brought to the surface of the material are entrained and carried out in the same way. In addition the fluid current or stream penetrates the mass of material to a certain extent, assing between the interstices, thereby dislodging fines and entraining them. lhe fines are discharged at the outlet 9 of the ejector.

It will be noted that the amount of fines carried or propelled by the fluid stream within the mill increases in the direction of the apex of the mill. It is therefore important that the velocity of the fluid stream, and consequently its entraining and carrying power, should increase in the direction of the outlet 4. Hearing in mind that the velocity at any point of a stream is inversely proportional to the cross-section of the stream at that point, it will be seen that the velocit cone 2 is east at the base of the cone and increases as the apex is approached. The velocity is greatest at the outlet 4 so that the current possesses the necessary entraining and removing power at this point although its velocity at the base of the cone 2 may be only that required to entrain and remove the relatively small amount of fines.

Instead of, or in addition to, creating a negative pressure or suction at the outlet 4 in order to pass same result may be attained by forcing elastic fluid into the drum through a suitable The elements 1, 2, 3 and 4 correspond to I those similarly designated in Fig. 1 and need no further description. Air or other elastic fluid under pressure is introduced through a. stationary pipe 12 which discharges below the surface of the. material at a point spaced from the outlet opening 4.. This passage of motive fluid upwardly through the material dislodges any fines which may adhere to the larger particles of material and the fines are discharged through the opening 4 through which the current of motive fluid passes. While the means 12 may be relied on to establish a current of elastic fluid portion 2 and opening 4 by substantially that the elastic motive fluid ot' the fluid passing through the.

the current of elastic fluid 'through the outlet portion 2, broadly the through the outlet closing the inlet 3, I prefer to provide an additional source of fluid shown as a. jet 14 supplied with fluid under ressure through a stationary conduit 15. It will be noted under pressure is in effect discharged within the mill at or ad'acent the base of the conical outlet of the mi 1. A fan or blower F, or other suitable source of elastic fluid may be employed to supply the jets of nozzles through the pipes 12 and 15. The said jet is directed toward the outlet opening and together with the converging port-ion 2 of the rotatable drum 1 forms an ejector whose outlet is at 4. By virtue of the structure described the fines within the mill are entrained and removed from the mill b a fluid stream of increasing velocity towar the apex of the cone. desirable a plurality of lifting vanes 16 may be provided within the cone portion 2 for the purpose of periodically elevating portions of the material and dropping the same into the more active portion of the fluid stream.

In accordance with the provisions of the patent statutes, I have herein described the principles of operation of my invention, together with the apparatus which I new consider to represent the best embodimentsthereof but I desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out b other means. Also, while it is designe to use the various features and elements in the combinations and relations described, some of these may be altered and others omitted and some of the features of each modification may be embodied in the other without interfering with the more general results and effects outlined, and the invention extends to such use.

It will be understood of coursethat the mills embodying the present invention may be provided with any suitable grinding media and with other desirable" appurtenances and auxiliary devices well known in the art.

What I claim is:

The combination with a conical grinding mill comprising a rotatable drum having a conical outlet portion for automatically classifying material according to size, provided with an outlet opening for dischargting the material when ground, of ajet which discharges into said conical outlet portion adjacent the base thereof and directed toward said outlet opening, said jet and conical outlet portion cooperating to form an ejector and means for supplying elastic motive fluid to said jet under pres sure.

In testimony whereof I hereto afiix my signature.

HARRY W. HAR-DINGE.

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