US1589740A - Pulverizing mill - Google Patents

Description

June 22 1926. 1,589,740

L. c. BONNOT ET AL PULYERIZING MILL File J ly 1925 2 Sheets-$heet 1 June 22 1926. '4 1,589,740

L. c. BONNOT ET AL PULVERIZING MILL Fild July 1925 2 Sheets-Sheet 2 .ZZZ.

01152? 6130117201 and saw/M Patented June 22, 1926.

v UNITED STATES PATENT OFFICE.

LOUIS C. BONNO'I, OF LOUISVILLE, AND WILLIAM M. BARKER, OF CANTON, OHIO, AS- BIGNORS TO THE BONNO'I COMPANY, OF CANTON, OHIO, A CORPORATION OF OHIO.

PULVERIZING MILL.

Application filed July 30, 1925- Serial N0. 47,039.

The invention relates to a rotary drum grinding or pulverizing mill partly filled with balls or the like, the material to be pulverized bein fed into one end of the drum and the pn verized material being withdrawn from the other end thereof by means of an exhaust fan.

The object of the improvement is toprovide a machine of this character having means for preventing the balls from being thrown or drawn into the fan, damaging the same; to provide for returning any balls or coarse material to the drum, which may be thrown therefrom into the inlet or outlet portions thereof; to provide for a decreased suction at the exhaust end of the drum 1n order to pick up only the finely pulverized portions of material, the suction being increased toward the fan for the purpose of quickly exhausting the same; and to greatly reduce the suction through the axial center of the drum, upon the inlet end thereof in order to feed the heavier or coarser particles of the material toward the peripheral portion of the drum where they will be acted upon by the balls.

The improved mill is well adapted for pulverizing small lump or slack coal for use in a furnace or powdered fuel feeding system, although it is equally adaptable for pulverizin other coarse or granular materials.

M ills of this type usually include an axial tube, extending into the drum, through which the powdered material is discharged as by the suction fan. The present improvement contemplates the elimination of the axial tube, the raw material being fed through an axial opening in one end of the rotatable drum, a perforate baflle plate being located at the center of this axial opening, breaking the suction through the axial center of the drum and causin the greater amount of the material to be ed around the periphery of said baflle plate. through an inwardly flared cone, toward the peripheral portion of the drum and into direct engagement with the balls which are bein continuously thrown around within the same; the "powdered material being withdrawn through an axial cone or funnel discharge protruding from the other end of the drum and communicating with the exhaust fan, splral ribs being provided therein to return an balls which are thrown upward into sai discharge cone.

The inlet and outlet cones of the rotatable drum terminate in reduced cylindrical neck portions provided with reversely disposed spiral ribs for returning any balls or large particles of material which may be thrown from the drum, as well as for feeding coarse material into the drum from the inlet end thereof; and a coarse mesh screen may be provided between the exhaust or outlet end of the drum and the exhaust fan to prevent balls or coarse particles of material from being thrown from the drum into the fan.

Apparatus embodying the present invention is illustrated in the accompanying drawings, forming part hereof, in which,

Figure 1, is an axial section through the improved pulverizing mill, and

Fig. 2, a transverse section of the same taken substantially on the line 2-2, Fig. 1.

Similar numerals of reference indicate corresponding parts throughout the drawin s.

The grinding drum 3, may be rotated in any usual manner as by the ring gear 4 and the pinion 5 meshing therewith and mounted upon the drive shaft 6, journaled in bearin s 7 supported upon the base 8.

he inlet or feed cone 9 is connected to one end of the drum as by the annular flange l0 and bolts 11, and provided with the reduced, cylindrical feed neck 12 which. may be rigid y connected to the cone as by the flanges 13 and bolts 14.

A perforate disk 15 is mounted within the feed opening 16 of the drum and provided with the radial lugs 17 which extend into sockets 18 formed in the flange 10 of the feed cone, the connecting bolts 11 extending through said lugs. The peripher of the perforate disk, as shown in the rawings, is spaced from the periphery of the feed opening, permitting the greater part of the g material to be fed around said disk, toward the peripheral portion of the drum, the perforate disk permitting a portion of the air to be drawn axially through the drum while at the same time breaking the direct axial draft through the drum and preventing the bulk of the material from being carried from the feed opening directly into the outlet or discharge end of the drum.

The discharge or exhaust cone 19 is connected to the discharge end of the drum as by the annular flange 20 and bolts 21 and has rigidly connected to its outer end the reduced, cylindrical discharge neck 22, which may be attached to the cone as by the annular flanges 23 and bolts 24.

The necks 12 and 22 may form journals for supporting the drum, being rotatably mounted within the bearings 25 supported upon the uprights 26 which are mounted upon the base 8.

The exhaust fan is mounted within the fan casi g 27 axially aligned with the drum and provided with the stationary exhaust spout 28 flared toward the exhaust neck 22 of the drum and preferably provided with the annular rib 30 upon which the annular groove 31 of the rotatable exhaust neck is journaled. The exhaust fan may be rotated as bythe motor 32.

A sump 33 may be provided in the lower side of the exhaust spout 28 and normally closed by a hinged trap door 3 1 controlled as by a counter weight 35, to permit any balls which are accidentally carried into the exhaust spout to be removed therefrom and returned to the drum. If desired, a coarse mesh screen 36 may be located in the exhaust spout as a positive precaution against any of the balls being thrown or carried into the exhaust fan, and a clean-out door 37 may be provided above said screen for the purpose of removing lint and the like from the screen.

The material to be pulverized is fed into the inlet or feed neck of the drum as by the inclined tube 38, and for the purpose of carrying coarse particles of the material into the feed cone, as well as for returning any of the grinding balls 39 whiclr may be thrown upward into the said neck, a spiral rib 40 is provided in the feed neck.

A similar rib 41, reversely disposed to the rib 40, is provided in the outlet neck for returning any coarse material or grinding balls which may be thrown into the same, and for the purpose of carrying back into the drum, any grinding balls which may be carried upward into the exhaust cone 19, a plurality of spiral or angular ribs 42 are provided upon the interior of the cone and extended over the inner face of the annular flange 20 thereof.

By these means the material to be pulverized is passed into the inlet or feed cone, the suction from the exhaust fan pulling the material through the cone, around the periphery of the perforate battle plate 15, and into the drum, only the very finest particles charge end t of the material being carried through the perforations of said plate to the fan. The material is thrown around in the drum, with the balls, by centrifugal action, pulverizing the same, only the very finest particles of the pulverized material being exhausted through the fan, as the area of the charge end of the discharge cone 19 is several times greater than the discharge end thereof, so that there is a very slow speed of suction into the large end of the cone and a greatly accelerated speed of suction at the small end thereof.

Thus only the very finest particles of ground material are drawn into the exhaust fan, and the same may be delivered into any usual construction of dust collector and the free air returned therefrom, if desired, directly into the feed end of the mill. Since only the very finest material is exhausted from the ball mill by means of the suction fan, it will be'seen that the material is discharged with such uniformity that it need not be graded or classified but can be discharged directly into the dust collector or other device.

By the construction shown the coarser particles of material, as well as the grinding balls, cannot be drawn into the discharge cone by the reatly decreased suction at the hereof, and should any of these coarser particles be thrown into the discharge cone or carried into the same by centrifugal motion, they, will be immediately carried back into the drum by means of the'spiral and angular ribs therein.

The formation of the discharge cone and the means for repelling the entrance'of gr nding media and coarse materials into the mouth thereof, which are described but not claimed herein, are included in the subject matter of a continuing application, Serial No. (36,855, filed November 4, 1925, by these applicants.

We claim:

1. A pulverizing mill including a rotary drum with grinding balls therein, an exhaust fan communicating directly with the drum and means for positively preventing grinding balls from entering the fan.

2. A pulverizing mill including a rotary drum with grinding balls thereln, an exhaust fan communicating directly with the drum and a screen between the drum and fan for preventing grinding balls from entering the fan. I

3. A pulverizing mill including a rotary drum with grinding balls therein, an exhaust fan communicating with one end of the drum, an axial feed opening in the other 1 end of the drum, and a perforate disk located in the center of the feed opening.

4. A pulverizing mill includin a rotary drum with grinding balls therein, an exhaust fan communicating with one end of the drum, a feed cone flared inward at the other end of the drum and a perforate plate lfocated in the feed cone and spaced thererom.

5. A pnlverizing mill including a rotary drum with grinding balls thereln, an exhaust fan comnmnicating with one end of the drum, :1 feed cone flared inward at the other end of the drum, and a perforate plate located in the larger end of the feed cone and spaced therefrom.

In testimony that We claim the above, We have hereunto subscribed our names.

LOUIS C. BONNOT. WILLIAM M. BARKER.

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