US2526355A - Pulverizing apparatus - Google Patents

Description

Oct. 17, 950 A. HESSE PULVERIZING APPARATUS 2 Sheets-Shea?! 1 Filed March 21, 1946 Fig.2

14D OLF HESSE' Oct. 17, 1950 A. HESSE 2,526,355

PULVERIZING APPARATUS Filed March 2l, 1946 2 Sheets-Sheet 2 HDOLF' HEssE Patented Oct. 17, 1950 PULVERIZING APPARATUS Adolf Hesse, Worcester, Mass, assignor to Riley Stoker Corporation, Worcester, Mass, at corporation of Massachusetts Application March 21, 1946, Serial No. 656,002 6 Claims. (Cl. 241-171) This invention relates to pulverizing apparatus, and more particularly to apparatus of the type including a generally horizontal rotatable drum which contains loose grinding bodies arranged to pulverize material within the drum, such apparatus being ordinarily known as ball mills or tube mills.

In order to obtain high capacity from such apparatus, it is important to remove particles of material from the drum as soon as they have reached the desired degree of fineness. If particles are permitted to remain in the drum too long, they will continue to be ground until they become finer than is either necessary or desirable, and this results in a very marked reduction in the capacity of the apparatus.

It is often necessary for the pulverizing apparatus to handle material containing consider able moisture, and this has caused many difficulties in the past, particularly in that the capacity of the machine is greatly reduced with such material. In extreme cases the wet material has become packed in a thick layer completely covering the inner cylindrical surface of the drum, so that the grinding bodies dropping against this layer have no effect whatsoever in pulverizing the material. This ma make it necessary to shut down the machine, so that workmen may enter the drum and break up the layer of packed material with hand operated tools. The delay and inconvenience arising from such a situation is a serious and expensive matter.

It is accordingly one object of this invention to provide a novel construction and arrangement for a pulverizing apparatus of the type comprising a rotatable drum containing loose grinding bodies, such that the capacity of the apparatus will be greatly increased.

It is a further object of the invention to provide a pulverizing apparatus of the type comprising a a pulverizing apparatus of the type comprising r a rotatable drum containing loose grinding bodies, so constructed and arranged that comparatively wet material may be pulverized at a high rate and packing of such material against the drum wall may be avoided.

, the drum. This subjects the incoming material With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

Referring to the drawings illustrating one embodiment of the invention, and in which like reference numerals indicate like parts,

Fig. l is a longitudinal section through a ball mill of the air swept type;

Fig. 2 is a view similar to Fig. 1, but showing a modification in which the direction of air flow is reversed;

Fig. 3 is a longitudinal section through a further modification showing a ball mill of the gravity discharge type; and

Fig. 4 is a view similar to Fig. 3, but showing "a slightl modified construction in which the from the opposite end of trunnions being rotatably supported in suitable bearings I5 and 16 respectively.

An annular gear I 8 is secured to the drum, and it will be understood that this gear is driven in known manner by a suitable pinion (not shown). Thus the drum will be rotated, and material within the drum will be pulverized by the impact of the cascading balls I l upon the material. The fine material will be carried out of the drum by a current of a suitable gas, such as air, which travels through the drum, the air preferably being heated in known manner before entering the drum, if wet material is to be pulverized. As shown, the air may enter the trunnion [2 from a stationary conduit 2!], and it may escape from the trunnion l4 through a conduit 2| leading to a fan 22.

The material to be pulverized is thrown or projected into the drum in a stream which passes through the trunnion l4 and above the surface of the bed of material in the lower portion of to intimate contact with the stream of hot air within the drum, promoting a very eiiective drying of the material. Particles of the incoming material which are already sufficiently fine will be picked up immediately by the air stream and carried out of the drum in suspension, while the coarser particles will be deposited in the drum and pulverized by the cascading balls I l.

.ated wet particles.

While various devices may be employed within the scope of the invention to project the material into the drum, I preferably use a revoluble mechanical device for this purpose. In the illustrated embodiment a transverse horizontal shaft 2 is rotatably supported close to and in front of the trunnion I4, this shaft having blades or paddles mounted thereon which revolve within. a semi-cylindrical casing 26, the casing being open upwardly and rearwardly toward the trunnion. The shaft 24 is driven by any suitable means, preferably in such a direction that the upper blades 25 will travel rearwardly. A flat horizontal plate 28 is slidably mounted in front of and above the casing 25, the rear edge of the plate overlying the shaft 24. This plate may be adjusted forwardly and rearwardly by means of a screw 29. A ram 3| is slidably supported on the upper surface of the plate 28, this ram being reciprocated in a forward and rearward direction by a rocker arm 32 driven byany suitable and well-known means having provision for controlling the amplitude or frequency of the ram strokes. A hopper 34 is mounted above the ram 3|, the rear wall 35 of the hopper being adjustable vertically by means of a screw 36. A chute or down-spout 38 leads from an overhead bunker or the like (not shown) to the hopper 34.

The operation of this embodiment will now be apparent from the above disclosure. drum it rotates, the balls H and the mass of material in the bottom of the drum will be continuously carried upwardly and caused to cascade downwardly in a well-known manner, so that the material will be pulverized by the impact of the balls. Ihis will cause a cloud of fine material to arise in the drum, and this fine material will be picked up and carried along by the current of air which is drawn through the drum by the fan 22. Coarse material will be supplied to the hopper 34 by the down-spout 38, and the reciproeating ram 3| will deliver the material at a controlled rate to the revolving blades 25, which will project the material rearwardly through the trunnion 54 into the drum to maintain the material therein at a desired level. While the blades 7 25 do not revolve at a sufficient speed to function as pulverizing elements, they will nevertheless serve to break up lumps consisting of agglomer- This will expose a much greater surface area of the material to the stream of hot air and thereby greatly reduce the moisture content of the material before it is deposited in the lower portion of the drum. A considerable portion of the material projected into the drum may already be of sufficient fineness to be carried in suspension by the air stream passing through the drum. Consequently such particles will not be deposited in the drum, and the balls I! will be left free to operate upon particles which require further reduction instead of being cushioned to a considerable extent by an accumulation of particles which are already fine enough. Since the drum H1 is horizontal and generally cylindrical, the balls U will arrange themselves automatically in a substantially uniform manner along the drum, irrespective of the ball size.

' The coarse particles projected by the revolving blades 25 will be distributed throughout the length of the drum, instead of being deposited only at one end of the drum as heretofore. Consequently the pulverizing action will be substantially uniform from one end of the drum to the other. This uniformity of pulverizing action, the improved drying of the incoming material, and

As the the prompt removal of sufficiently fine particles enterin the drum all contribute toward a very pronounced increase in the pulverizing capacity of the mill. The plate 28 may be adjusted to control the trajectory of the stream projected by the blades 25, and the hopper wall 35 may be adjusted if necessary to prevent avalanching of the material from the hopper 34 over the rear edge of the plate 28.

In Fig. 2 there is shown a slightly modified form of the invention, in which the direction of the air flow through the drum is reversed as compared with Fig. 1. Thus in Fig. 2 the air enters the trunnion M from a stationary conduit 4|], and it escapes from the trunnion l2 through the conduit 20 and a conduit 4| leading to'a fan 42. The various other parts of the apparatus may be similar to the correspondingly numbered parts in Fig. 1.

In the operation of the embodiment shown in Fig. 2, the revolving blades 25 will project material through the trunnion |4 into the drum H where it will be pulverized by the impact of the cascading balls The current of air produced by the fan 42 willtravel through the drum in the same general direction as the material thrown by the blades 25. It will ordinarily be desirable to rotate the shaft 24. at a somewhat lower speed in the Fig. 2 arrangement: than in Fig. 1, since in the latter case theproje'cted material must travel in opposition to the air stream and hence requires a higher initial velocity. In both cases the same advantages are obtained in rapid drying of Wet particles, proper distribution of material lengthwise of the drum, and prompt removal ofv fine particles by the air stream.

In Fig. 3 there isshown a further modification'of the invention in which there. is no airsweeping of the drum. The trunnion I2 is closed by a plate 44, and the trunnion i4 is flared forwardly at 45 to discharge fine particles of material by gravity into a laterally inclined trough 46. To permit such. discharge, the casing 26 and the various associated parts of the feeding mechanism are located at a somewhat higher elevation than in Fig. 1.

In the operation of the embodiment shown in Fig. 3, the revolving blades 25 will project material through the trunnion |4 into the drum l0, and the cascading balls H will pulverize the material. The fine particles of material will be discharged by gravity through the trunnion M into the trough 46. By breaking up lumps of agglomerated particles, and by providing a more uniform distribution of the incoming material along the drum, the blades 25 will make it possible to operate satisfactorily at high capacity.

In Fig. 4 there is shown a further modification of the invention, the construction being similar to Fig. 3 but arranged to discharge the fine material from the opposite end. Thus in Fi 4 the trunnion I2 is flared rearwardly at to discharge the fine material by gravity into a laterally inclined trough 5l. The casing 26 and the other parts of the feeding mechanism are located. somewhat lower than in Fig. 3, and the trunnion I4 is provided at its front end with an inwardly projecting annular flange 52 to prevent material within the drum from spilling into the casing 26.

The operation of the embodiment shown in Fig. 4 will be substantially the same as that of the Fig. 3 construction, except that the fine particles of material will be discharged through the trunnion I2 into the trough 5|. Preferably the shaft 24 is rotated at a somewhat lower speed, or the spill plate 28 is adjusted slightly to the rear, so that none of the incoming material will be projected entirely through the rear trunnion I 2.

It will be apparent that in each of the embodiments illustrated the material is projected into the drum through the hollow trunnion [4, any agglomerated lumps of material being broken up before they reach the bed of material in the bot tom of the drum, and the incoming material being distributed far more uniformly along the drum than with prior constructions. Wet material will be considerably dried while in suspension during its flight through the air, this effect being particularly pronounced if the drum is swept by a current of hot air. Furthermore, this air current will pick up and carry along not only the fine particles produced by the pulverizing action of the balls H but also any fine particles which enter the drum with the coarse material. All of these various effects combine to provide a very marked increase in the pulverizing capacity of the mill.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A pulverizing apparatus comprising a substantially horizontal drum of generally cylindrical form rotatable about its axis and having an opening at one end, loose grinding bodies within the drum and free to distribute themselves throughout the length of the drum during the rotation thereof, a movable blade mounted adjacent the opening, means to feed material to be pulverized to the blade, and means to move the blade in such a manner as to cause the blade to throw the material through the opening into the drum and distribute the material throughout substantially the entire length of the drum for pulverization by the said grinding bodies.

2. A pulverizing apparatus comprising a substantially horizontal drum of generally cylindrical form rotatable about its axis and having an opening at one end, loose grinding bodies within the drum and free to distribute themselves throughout the length of the drum during the rotation thereof, revoluble blades located adjacent the opening, means to feed material to be pulverized to the blades, and means to revolve the blades in such a manner as to cause the blades to throw the material through the opening into the drum and distribute the material throughout substantially the entire length of the drum for pulverization by the said grinding bodies.

3. A pulverizing apparatus comprising a substantially horizontal drum of generally cylindrical form rotatable about its axis and having an opening at one end, loose grinding bodies within the drum and free to distribute themselves throughout the length of the drum during the rotation thereof, blades located adjacent the opening and revoluble about a substantially horizontal axis transverse to the axis of the drum, means to feed material to be pulverized to the blades, and means to revolve the blades at such a speed as to cause the blades to throw the material through the opening into the drum and distribute the material throughout substantially the entire length of the drum for pulverization by the said grinding bodies.

4. A pulverizing apparatus comprising a substantially horizontal drum of generally cylindrical form rotatable about its axis and having an opening at each end, loose grinding bodies within the drum and free to distribute themselves throughout the length of the drum during the rotation thereof, means to produce a current of gas which enters the drum through one of the openings and escapes through the other opening, revoluble blades located adjacent one of the openings, means to feed material to be pulverized to the blades, and means to revolve the blades in such a manner as to cause the blades to throw the material through the adjacent opening into the drum and distribute the material throughout substantially the entirelength of the drum for pulverization by the said grinding bodies.

5. A pulverizing apparatus comprising a substantially horizontal drum of generally cylindrical form rotatable about its axis and having an opening at each end, loose grinding bodies within the drum and free to distribute themselves throughout the length of the drum during the rotation thereof, means to produce a current of gas which enters the drum through one of the openings and escapes through the other opening, blades located adjacent one of the openings and revoluble about a substantially horizontal axis transverse to the axis of the drum, means to feed material to be pulverized to the blades, and means to revolve the blades at such a speed as to cause the blades to throw the material through the adjacent opening into the drum and distribute the material throughout substantially the entire length of the drum for pulverization by the said grinding bodies.

6. A pulverizing apparatus comprising a substantially horizontal drum of generally cylindrical form rotatable about its axis and having an opening at each end, loose grinding bodies within the drum and free to distribute themselves throughout the length of the drum during the rotation thereof, means to produce a current of gas which enters the drum through one of the openings and escapes through the other opening, blades located adjacent the gas escape opening revoluble about a substantially horizontal axis transverse to the axis of the drum, means to feed material to be pulverized to the blades, and means to revolve the blades at such a speed as to cause the blades to throw the material through the adjacent opening into the drum in opposition to the current of gas and distribute the material throughout substantially the entire length of the drum for pulverization by the said grinding bodies.

ADOLF HESSE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 567,513 Ruelle Sept. 8, 1896 672,833 Scheirer Apr. 23, 1901 1,321,201 Young Nov. 11, 1919 1,331,969 Tomlinson Feb. 24, 1920 1,427,234 Sherban Aug. 29, 1922 1,819,093 Hardinge Aug. 18, 1931 2,020,871 Beers Nov. 12, 1935 2,128,848 Rafetto Aug. 20, 1938 2,174,630 Hardinge Oct. 3, 1939 FOREIGN PATENTS Number Country Date 395,912 Great Britain July 27, 1933

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