US1759134A - Pulverizing apparatus - Google Patents

Description

May 20, 1930. 5 RlLEY ET AL 1,759,134

PULVERiZING APPARATUS Filed Nov. 1925 4 Sheets-Sheet 1 WY lnll INYENTORS. I WITNESSES RSAA FORD RILE My? OLL/SON CRA/Q BY [Jam m May 20, 1930. Rs. RILEY l AL 1,759,134 m PULVERI Z ING APPARATUS Filed Nokr. 7. 1925 4 Sheets-Sheet 2 INVENTORS R. SANFORD RILEY 5 OLL/50N CPA/6 A RNEY WlTNE SSES May 20, 1930. R|| EY El AL 1,759,134

PULVERIZING APPARATUS Filed Nov. 1925 4 Sheets-Sheet 5 INVENTORS WITNESSES R. SAM-"0RD RILEY M OLL/SON CPA/6 May 20, 1930. r 5, ET AL 1,759,134

PULVERI Z ING APPARATUS File Nov- 1925 4 Sheets-Sheet 4 FIG. F|6.9

INVENTORS R SANFORD R/LE Y OLL/SO/V CRA/G WITNESSES ,MA v

. HTTO RN Patented Ma 20, 1e30- STATES PATENT OFFICE ROBERT SANFORD RILEY AND OLIiIS ON CRAIG, OF WORCESTER, MASSACEUSETTS, AS-

SIGNORS TO RILEY STOKER CORPORATION, OF WORCESTER, MASSACHUSETTS, A

CORPORATION OF MASSACHUSETTS PULVERIZING APPARATUS Application filed. November This invention relates ,to-pulverizing machines and more particularly to a machine of the beater type arranged to comminute solid material and mix it'with air for transportation as desired.

A machine of the type shown in the'United States patent to Blyth, No. 1,446,151, of Feb. 20, 1923, comprises a rotatable disk which has pegs on opposite sides thereof interfitting with stationary pegs on the casing walls and between which the material is pulverized by impact and attrition. The machine has two grinding zones on opposite sides of and connected by an annular passage around the disk. In the first zone, the material is crushed as it is thrown outwardly by the,

centrifugal action of the revolving pegs and is caused to pass around the edge of the disk into the second grinding zone. Here it' is forced to travel inwardly against the centrifugal action of the revolving pegs toward acentrally disposed outlet.

The Blyth type of machine is particularly adapted for pulverizing coal and feeding it to a furnace burner in condition for com bustion, but there are certain defects inherent in the construction which render it inefficient for such purposes. The pegs are relatively fragile'and they are so arranged that if a large and hard foreign body, such as a chunk of iron, should be fed to. the machine, a number of the pegs may be brokenfrom their fastenings and these in turn aid in the destruction of the remaining pegs in that grinding zone. There moreover has been excessive wear on the pegs due to the necessity for the pegs to crush the coarse material preliminarily,- whereas it is found that such an arrangement serves more e'fliciently for the final stages of pulverlzation. The relativelylarge surface of the revolving pegs causes a high air pressure opposing the effort of the fan to move the material through the casing and sets up considerable wasted internal friction, which results in the power consumption of the machine being excessively high.

It is accordingly the primary object of our invention to overcome these difficulties and provide a unitary and simply constructed 7, 1925. Serial No. 67,639.

rial to a desired degree of fineness, and in which the consumption of power per unit of material pulverized is greatly reduced below that heretofore required to obtain similar results.

Further objects are to minimize the danger of breakage of the pulverizing members and to provide means for removing hard and large foreign bodies safely from the machine. Other objects will be apparent in the following disclosure.

In accordance with one aspect of our invention we have provided a hammer mill construction arranged to crush coarse mate rial effectively and to safely eliminate large and hard foreign bodies, such as tramp iron. As a further feature, we have provided a pulverizing apparatus having two interdependent and connected zones, the second for the fine pulverization and the first for preliminarily crushing the coarse material and eliminating the foreign bodies so as to protect the pulverizing elements in the second zone from breakage.

A unitary construction embodying all of the features of our invention may comprise in. the second zone rapidly revoluble bodies, such" as pegs, which act by impact and attrition to comminute the material fed thereto. These may be so arranged that the centrifugal force set up tends to aid inobtaining fine pulverization, as is the case where the impact members are arranged between an annular inlet outside of their path of revolution and a central outlet located near their axis. For preliminarily crushingthe coarse material in the first zone, we propose to em- -ploy revoluble impact members so constructed and arranged that they cannot be easily broken, and for such implements we prefer to use relatively heav hammers -mountedat their ends on a rapidly rotated shaft. The foreign bodies may be retained in this crushing zone until reduced to a fine'size, but they are preferably eliminated from the hammer mill and removed from the machine. feet such elimination, we place a plate such. as a perforated grid outside of the path of the revolving hammers, and this grid is so To eflocated that the crushed material which escapes from the hammers may be distributed and fed directly into the periplferal portion of the second grinding zone. In order to catch the large foreign bodies, the grid may be so shaped as to provide a large aperture which communicates with a space located to receive'such bodies. The grid is preferably located adjacent to the inlet to the second zone but spaced therefrom to form an annular passage within which the tramp iron hurled through the aperture may find its way to a receptacle at the bottom of the casing.

This apparatus preferably takes the form of a substantially cylindrical casing having an inlet and an outlet and within which a disk is mounted on a rapidly rotated shaft. The disk is spaced laterally and peripherally from the casing wall to form two connected zones. A fan is mounted on the shaft and arranged to propel the material through the apparatus. Revolving pegs are mounted in g the outlet zone on one face of the disk and preferably cooperate with stationary pegs on the opposite casing wall, and these areyarranged between the annular passage around.

fine pulverization'while preventing the escape thereto of large sized bodies. A rejector, preferably comprising a set of revolving blades, may be provided to prevent the escape of coarse material from the second zone and to return it for further treatment by therevolving pegs. V

Referrin to the drawings which illustrate certain em odiments of our invention, and in which like reference numerals indicate like parts:

Fig. 1 is a vertical sectional view with parts removed showing the interior of the pulverizingcasing and the fan chamber;

Fig. 2 is a vertical elevation of the entrance side of the machine with the cover partly re moved and parts broken away for the sake of clearness of illustration;

. Fig. 3 is a section on the line 33 of Fig. 1, but reduced in size;

Fig. 4 is a similarly reduced section on the line 1-4 of Fig. 1 with parts shown in elevation and others partly removed;

Fig. 5 is an isometric view of a grid section; I

Fig. 6 is a detail showing the manner of mounting the pegs;

Fig. 7 is a detail showing the construction of a rejector blade;

Fig. 8 is a vertical section partly broken away showing a modified form of our invention;

Fig. 9 is a detail of a portion of the construction of Fig. 8 showing the operation of the swing hammers;

Fig. 10 is a detail showing the grid and swiing hammers of the form shown in Fig. 8; an

Fig. 11 is a detail showing a modified form of grid.

The embodiment of our invention illustrated inFigs. 1 to 5-inclusive comprises two intercommunicating cylindrical casings 10 and 11, the first of which forms the pulverizing casing and the second a fan casing. Mounted in suitable bearings 12 at each end thereof is a shaft 13, rotated rapidly by suitable means, which passes centrally through the two casings 10 and 11 and is arranged to carry the pulverizing-rotor'and the fan. A rotor, which in the present instance is shown as a disk 15, is mounted within the casing 10 on the shaft 13 to rotate about its axis, and this disk is spaced laterally from the interior walls of the casing to form two grinding zones 16 and 17 The periphery of the disk is also spaced from the inner periphery of the substantially cylindrical'casing 10 so as to form anannular passage 18 around the 'disk which connects the two grinding zones.

This disk 15 may be suitably, fastened to the shaft 13, as by means of a sleeve 19 keyed to the shaft which has a flange 20 thereon arranged to be bolted to the disk andto removablyrsupport it;

The preliminary crushing operation may be accomplished by means of hammers,'which in the-present instance comprise straight bars of iron 25 pivotally mounted on pins 26 which pass through the flange 20 and two other flanges 27 and 28 formed integral with the sleeve 19. The bars may be provided with holes 29 at each end (Fig. 2) which permit interchanging the ends after the hammers have become worn. The material to be crushed is introduced from a suitable feeding apparatus through the spout 3O communicating with an opening 31 in the side wall of the casing 10, which may be suitably located but is shown adjacent to the shaft 13.

As an effective aid in. the preliminary crushing o eration, a plate or shelf 32 is arranged adyacent to the periphery of the revolving swing hammers and serves to hold the material within the crushing zone for a certain length of time. It will be observed that this plate 32 is spaced by a considerable distance from the inner peripheral wall of the casing 10. This annular space 34 is provided to permit the escape of hard foreign bodies from the pulverizing zone and to aid in causing an even distribution of the crushed material into the second grinding zone. As shown particularly in Figs. 3 and 5, this plate is in the form of a perforated grid which may llU which enters the casing passes in the direction of the arrows with the revolving hammers and. is thrown-outwardly through the openingi'into the annular space 34," whence itultimately seeks the lower portion of this annular space and drops into the pocket 38 provided at thebottom. of the casing 10f This foreign material may be removed,

through the slide door 39 suitably'fastened to the bottom of the pocket. It will be observed thatlzthis pocket extends completelyacross the bottom of the casing so that if foreign bodies should by any chance get into the second grinding zone they may likewise fall into this pocket and be removed from the path of the revolving impact elements.

This grid 32 is provided with openings 40 which are of such size and shape as is-best suited for the particular material being ground. These openings, which are not shown to scale, may be about% in diameter and they serve to permit material crushed by the hammers to escape radially through the periphery of the grid and thence get to the annular passage 18 around the rotor 15. The grid may, however, be made in various shapesfand configurations as desired. As shown in Fig. 11, the grid may extend all the way around the swing hammers but be provided at its. upper portion .with rather wide and large apertures 42 spaced by solid portionsof the grid 43' which are so arranged as.to permit material diflicult to crush to escape therethrough and yet to hold the crushable material within the grinding zone for a considerable length of time. The openings 44 in the bottom of the grid may be small as shown in Fig. 5.

It will now be een that in the first pul verizing zone, coarse material that enters the casing through the inlet 31 is struck by the .rapidly revolved hammers and is crushed thereby, the fines escaping radially through the openings 40 into the outer'annular zone 34'and the foreign bodies escaping into the pocket 38 provided for this purpose. The crushed material, which is fairly evenly distributed throughout the annular space 34, is

forced to pass through the annular passage- 18 around the disk 15 into thesecond zone, Where it meets the pulverizing action of a set of revolving impact bodies mounted on the disk and arranged to break the material by impact and attrition.

The pulverizing bodies in the second zone maycomprise a set of pegs mounted on the rotor which intermesh with a set of stationary pegs 51 mounted on the casing 42. Any suitable number ofrows of these pegs may be provided as desired, but we have found that two, as illustrated, are highly-efficient for pulverizing coal. The pegs may be variously arranged and of different lengths and sizes within the scope of our invention. As shown, the-pegs 51' extend sub.-

stantially the whole distance from the casing Wall 52 to the side of the rotor 15, whereas the pegs 50 mounted on the rotor are preferably short and are spaced by a considerable distance from the inner casing wall. This provides acomparatively quiet zone adjacent the casing wall through which the veryfine material'comingfrom the first grinding zone may escape'directly to theoutlet, and aids in the recirculation of the material.-

The pegs which maybe suitably formed preferably comprise iron bodies 53 cast in a flanged ferrule 54 0f drawn metal (see Fig.

6). The peg is mounted loosely within a hole in its support and the flange 55 of the ferrule is clampcdbetween the support and a clamping plate. The pegs mounted on the rotor have their flanges 55 held between the rotor disk 15 and a clamping plate 56 made up in a number of sections and boltedto the ;wise suitably fastened together. The peripher'al portions of the parts 60 and 61 makingup the'casing 10 are provided with liner sections 62 to receive the wear, which are adapted to be slid into place and there bolted to the. outer casing walls. In Fig. 4, theupper and one of the lower liners have been partially revolved or slid out of their correct positions to show how they are removed Inorder to make it easy to place the pegs on the casing walls, we mount the plate 58 in such a manner that it may also be revolved or slid around to a desired position so that the pegs in the lower part 60 of the casing may be moved around into the upper portion after the cover has been removed. To this.

end, the central tubular portion 65 of the fan from the second pulverizing zone projects casing 11 which forms theoutlet passage into the casing 10 (Fig. 1) and terminates'in a ring 66 fastened thereto. The plate 58 has a central cylindrical opening adapted to revolve on anouter cylindrical surface 67 of the ring 66, after it has been disconnected from the casing wall. The plate may be made in two or more parts, but they are connected together, as shown in Fig. 4%, so that the plate may be revolved as a unit and turned to anydesired position. Similarly, a liner plate 68 may be mounted on the side wall 36 of the casing 10 outside of the annular grid 32 in order to absorb the wear of the flying clouds of pulverized material. This plate may also be made up in sections arranged to be revolved around the flanged portion 85 of the grid so that the parts in the bottom of the casing 10 may be brought around to the upper half when the cover is removed for replacement.

As a safeguard to prevent the escape of large pieces of unbroken material and hard foreign bodies from the first zone into the second zone, we may provide a row of pegs 70 which project inwardly from the peripheral wall of the casing to a point close to the outer periphery of the disk 15. These may have their flanges clamped between the liner (S2 and the outer wall. Since the material in the first pulverizmg zone is revolving to a considerable extent due largely to the frictional drag of the rotor 15 and the impelling action of V the swing hammers, it will be seen that any foreign body is likely to strike the pegs 70 a glancing blow and so remain in the annular space 3i until it gets to the pocket 38, whereas the fine material may easily pass with the current of air between the pegs 70. These pegs are ordinarily spaced by a sufiicient dis tance to let coarse particles of crushable material be drawn by the fan suction into the second zone and so prevent clogging the first zone.

In order to prevent the escape of coarse particles from the second pulverizing zone, we provide a suitable reje ctor device which in the present instance comprises a series of blades 72 removably fastened by bolts 73 to a collar 7st keyed to the shaft 18. The rejector blade which may be of various shapes is illus trated in Fig. 7 as of a substantially U shape arranged with the open portion of the U fac ingin the direction of revolution of the blade. The blades, which revolve rapidly, are so shaped that they will scoop the coarse particles from ,the air as they attempt to pass through the outlet opening 76 within the tube and hurl. them back into the grinding zone. In order to aid this action, the ring 66 is provided with a beveled face 77 located close to the outer ends of the revolving blades 72 and so arranged that as the material is thrown outwardly from the U-shaped blades it strikes against this beveled face and is hurled back towards the rotor disk 15 and thence carried centrifugally into the path of the revolving pegs.

While the material may be moved through the casing by suitable means, we preferably introduce a supply of air into the preliminary crushing zone along with the material to be pulverized, and provide a suction fan arranged to draw the material against the centrifugal force set up by the revolving pegs and remove it from the casing. For this purpose a screened inlet 80 (see Fig. 2) is provided for the introduction of air from a suitable source of supply, and this air may be heated if desired to aid in drying the material being pulverized, as is often the case where a wet coal is being ground. In order to aid in introducing the material to be pulverized into the casing, a small opening 81 (see Fig. 1) is located adjacent the upper end of the chute 30 and is so arranged that as the coarse material moves downwardly into the casing a strong blast of air is drawn through the opening 81 along the bottom wall of the chute and so tends to keep the chute clean and insure the material moving uniformly into the pulverizer. The amount of air introduced through the opening 80 may be regu" lated by means of a suitable slide valve In the fan casing 11, a suitable type of suction fan 8a is mounted on the shaft 12:) to rota'te therewith. This fan serves both to move the dust cloud and to aid in mixing the air and the pulverized material. The space within the fan chamber terminates in a di:-:-

"charge pipe 85 (Figs. 1 and 2) which connects with a suitable pipe system for con veying away the material after it has been pulverized. If fuel is being pulverized for combustion purposes and more air is needed to aid in the combustion, a suitable rotary slide valve 86 may be provided in the side of the fan casing and arranged to introduce any desired quantity of air therein for mire ing with the cloud of pulverized fuel and air. The upper half of the fan casing 11, is removable, the same as is the cover (31 of the casing 10, in order that the blades of the tan 8-2 and the lin'er- 87 of the fan casing may be renewed as desired. It will be understood that the liner is made in at least two parts for this purpose and that the tube (55 and ring W3 are likewise split on a horizontal diameter so that the fan cover may be lifted off after the pulverizing casing cover has been removed. it is also to be noted that the upper grid section 32 is fastened to the inside of the cover 61, as shown in Fig. 2.

As a slight modification of the construction described above, we may provide pegs on both sides of the rotor. In the form shown in Figs. 8, 9 and 10, the rotor 90, corresponding with the rotor 15, has a set of pegs 91 mounted thereon and interfitting with stationary pegs 92 fastened to the casing wall which are arranged outside of the grid 93 surrounding the swing hammers 94. In this construction, the rotor is formed of two plates between which the flanges of the pegsare clamped. A further series of pegs 96 are mounted on the rotor in the second zone inter-fitting with.

z salsa.

the pegs 97 suitably fixed to the casing wall. While the construction of this modified form is otherwise substantially the same as that shown in Fig. 1, there are some detailed changes which might be mentioned. In this form, the swing hammers are all mounted with their inner ends in substantially a single plane. A collar 98 aids in clamping the disk plates 90 to a flange 99* of the sleeve 100 keyed on the rotatable shaft 101. Pins 102 pass through the flange and collar and carry the swing hammers 94c on their outer ends. The hammers are held from sliding 0d the pins by means of a further clamping collar 103 mounted on the shaft. In order that the hammers may cover substantially the whole inner surface of the grid 93, they are formed as shown in Figs. 9 and 10, one being bent to the left, another to the right, and an intermediate one sti-aight;

In using a machine of this form, reliance may be had on a magnetic separator to insure removal of iron from the coal to be ground, although if such a hard body should enter the casing, it could not break the swing hammers nor escape throughthe relatively small openings 105 placed preferably. all the way around the grid. This insures protecting the relatively fragile pegs 91 and 92 from severe shocks. which might cause their breakage; Coal is introduced "through the opening 106 and hot air through the opening 10? into the first zone, and the material is drawn through the second zone and between the rejector blades 108 into the fan casing 109 by means of the fan 110 mounted on the shaft 101.

The operation of this apparatus in so far as it can be understood, is somewhat as follows. While we may rotate the rotor at anysuitable speed, we prefer to give the pegs a velocity of at least 10,000 feet per minute if coal is to be pulverized. The fan which is so constructed as to create a powerful current of air through the machine, draws air through the openings 80 and 81 and forces it from the discharge pipe 85 which leads from the fan chamber.

The material to be pulverized, such as coal;

which is to be burned in a furnace, is introduced into the chute 30 in a suitable size, preferably lumps of not over'an inch in in diameter, and this material falling against the swing hammers 25 is struck a severe blow and there broken a by impact. While the coal opening 31 may be located at any desired point, we have shown it as adjacent the lower left hand portion of the grid circle. The rotor, revolving in the direction of the arrows in Fig. 3, causes the coal to be carried around with the swinging hammers and the hard foreign bodies, such as lumps of iron, are thrown out through the opening in the grid circle, shown at the upper right hand side of Fig. 3, and find their way to thepocket 88. The crushable material is forced partly through I the openings. 40 and partly out through the wide opening provided for the escape of hard bodies, and some may be carried around with the hammers for further crushing. Impact of the material against the upper portion of the casing liner oppo site the wide opening in the grid will also aid between the pegs70 and the rotor 15 and carrise the partially pulverized material with it.

The draft of the air through the casing is ordinarily such as to'keep the material moving rapidly and prevent any large accumulation of coarse particles at the bottom of the casing.

In the second zone, the material probably follows different paths depending upon its surface area and weight. It is thought that the very fine particles escape along the outer wall of v the casing between the stationary pegs 51 and'out of contact with the revolving pegs 50. This material may pass directly to the outlet 76 between the rejector blades 7 2, but the coarse particles are scooped out of the outgoing air current by these rejector blades and hurled back, in the direction of the arrowed line a in Fig. 1, into the path of the revolving pegs 50, and it then recirculates as indicated, disregarding the eddy currents set up by the pegs. This rejected material, as well as the coarse particles coming around the disk periphery, are struck repeatedly by the revolving pegs 50 and hurled against the stationary pegs 51 a large number of times with the result that ultimately the material is very finely pulverized. When it is sufiiciently small in size so that it may be borne like a cloud on the air current, it will pass between the rejector blades and so get into the fan casing. Here the fan blades serve to keep the cloud of'dust and air thoroughly mixed and to force it outwardly through the discharge opening into a suitable conveyor pipe to carry the material to the furnace burner or elsewhere as desired.

The rate of pulverization and the degree 0 placed by other forms which will be more or' less eficient in scooping out the coarse particles from the dust cloud. It will be seen that the centrifugal force setup in the first zone causes a radial flow of the material and aids largely in distributing the crushed material throughout the annular passage around the disk, whereas the centrifugal force in the secmay employ various features or" the inven-' tion in other arrangements and combinations within the scope of the appended claims.

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

1 A pulverizing apparatus comprising a casing having an inlet and a centrally located outlet, means forming two peripherally communicating grinding zones adjacent to the same, revoluble heaters within the outlet zone arranged to pulverize the material transmitted thereto and means including revolubly mounted hammers within the inlet grinding zone which is arranged to crush the material preliminarily and prevent the escape of hard foreign bodies to the second zone.

2. A. pulverizing apparatus comprising a casing having an inlet and an outlet located centrally thereof, means forming two pulverizing zones adjacent the inlet and outlet which are connected by an annular passage, revoluble impact bodies in the outlet zone and yieldable impact members in the first zone which will crush the material without receivin substantial injury from hard foreign bodies and distribute the material radially to said annular passage.

3. A pulverizing apparatus comprising a casing having an inlet and an outlet located centrally thereof, means forming two pulverizing zones adjacent the inlet and outlet which are connected by an annular passage, rigid impact bodies revolubly mounted in the outlet zone and impact members in the first zone which will crush the material without receiving substantial injury from hard foreign bodies and distribute the material radially to said annular passage.

4. A pulverizing apparatus comprising a casing having a rotor mounted therein and arranged to form two communicating grinding zones on opposite sides thereof, means for introducing air and coarse material into the first grinding zone and for removing the pulverized material from the second zone, means including impact members in the first zone to crush the material, means for eliminating hard foreign bodies from the first zone, and means within the second zone to pulverize the material finely.

.5. A pulverizing apparatus comprising a casing havin a rotor mounted therein and arranged to form two grinding zones on opposite sides thereof and communicating around the periphery of the rotor, means providing for the introduction of air and coarse material into the first grinding zone, means forming an outletfor the pulverized material in the second grinding zones, impact bodies on the rotor in the second zone arranged to pulverize the material presented thereto, and means in the first grinding zone effective to crush the material preliminarily and prevent hard foreign bodies from passing to the second zone.

6. A pulverizing apparatus comprising a casing having an inlet and an outlet, a rotor mounted between the inlet and outlet and spaced from the casing walls to form two grinding zones connected by an annular passage around the rotor, means to cause a preliminary crushing of material in the first zone and distribute the material to said annular passage, means to effect a separation of hard foreign bodies from the material and prevent their escape to the second zone, and sets of attrition pegs mounted on the casing and the rotor in the second grinding zone arranged to pulverize the material fed thereto.

7. A pulverizing apparatus comprising a casing having an inlet and an outlet and two pulverizing zones connected with said inlet and outlet and which communicate annularly at the peripheral portion of the inlet zone, sets of in'ti'rfitting revoluble and stationary pegs in the outlet zone to pulverize the material and means including rapidly revoluble hammers in the first zone which will crush the material preliminarily by impact without receiving substantial injury from hard foreign bodies and distribute it for transmission to the second zone.

8. A pulverizing machine comprising a casing having an inlet on one side and a centrally disposed outlet on the other side, a disk rotatably mounted within the casing between said inlet and outlet and formim two grinding zones on opposite sides thereof: said disk being spaced from the casing pcripherally to form an annular passage from one zone to the other around the edge of the disk, impact bodies mounted on the casing and the rotating disk within the second zone, preliminary crushing members mounted within the first zone, and means cooperating therewith to cause foreign bodies to be separated from the material being pulverized and toprevent their passage into the second zone.

9. A pulverizing apparatus comprising a substantially cylindrical casing having an inlet and a centrally located outlet, a disk rotatably mounted within the casing and spaced from the walls thereof to form two grinding zones connected by an annular passage around the disk; interfitting sets of impact pegs on the casing and the disk in the sec I casin ond zone, impact members mounted to revolve with the disk in the first zone and arranged to crush the material preliminarily, and means permitting the escape of foreign bodies from the first zone without seriously damaging the. impact members therein.

10. A pulverizing machine comprising a casing having a centrally located inlet and a centrally located outlet on opposite sides thereof, a disk rotatably mounted in the casing between said inlet and outlet and spaced peripherally from the casing tb provide an annular passage from the inlet side of the disk to the outlet side, attrition pegs on the disk near the outlet and rapidly revoluble pivotally mounted impact hammers on the inlet side of the disk which are arranged to strike the material entering the inlet and give it a preliminary crushing blow, whence the material passes around the disk into the second grinding zone and against the centrifugal action of the rotating pegs through the outlet.

11. A pulverizing apparatus comprising a impact members revolubly mounted therein, and a plate adjacent to the peripheral path of said members and cooperating therewith to crush the material fed thereto, said plate being spaced from the casing to form an annular space and providing a large opening above the impact members through which hard foreign bodies may escape to said space andthrough which the pulverized'material may pass radially from the pulverizing zone.

12. A pulverizing apparatus comprising a casing, impact members revolubly mounted therein, means forming a free space outside of the path of said impact members and providing a passage through which hard foreign bodies may escape from the impact members to said space and through which the pulverized material may pass from the pulverizing zone, and meanspermittin'g removal of the foreign bodies from said space. 13. A pulverizing apparatus comprising a casing having a central inlet andanoutlet, a set of hammers revolubly mounted in the casin near the inlet, a plate adjacent to the perip ieral path ofthe hammers, said parts being'so constructed and arranged as to form a free space outside of the path of the hammers and provide a large opening through which large foreign bodies may escape from the hammers to said space, and means to propel the pulverized material from said space to said outlet.

14. A pulverizing apparatus comprisinga casing having an inlet and an outlet, a rotor therein, sets of interfitting impact bodies on the rotor and easing arranged adjacent the outlet to pulverize material fed thereto, and yieldable impact members adjacent the inlet which are revoluble with said rotor and a perforated grid adjacent the peripheral path thereof arranged to crush the material preliminarily and feed it to said impact bodies.

eign bodies.

16. A pulverizing machine comprising a casing, a shaft rotatably mounted therein,

revoluble hammers mounted on said shaft, a

grid adjacent to the peripheral path of said hammers and spaced from the casing wall and providing a large opening therethrough to permit hard foreign bodies to escape from the pulverizing zone into the space between 1 the grid and the casing, and a closure in the casing wall for removing such hard bodies without stopping the operation of the machine. Y

17. A pulverizing apparatus comprising a hollow casing, a grid located centrally within and spaced from the casing wall to form an annular passage, a shaft rotatably mounted Within the casing, hammers mounted on the shaft for revolving within the grid to pulverize material, said grid having fine openings for the escape of crushed material therethrough and providing a large opening for theescape of hard foreign bodies into the annular passa e and a closure at the bottom of the casing 0r removingsaid bodies from the passage.

18. A pulverizing apparatus comprising'a casing having an inlet and a centrally located outlet, a rotor therein arranged-to form two communicating pulverizing zones on opposite sides of the rotor and adjacent to the inlet and outlet respectively, hammers revolubly mounted in the inlet zone, a grid outside of.

casing, means therein forming two pulverizing zones which have an inlet and a centrally located outlet, impact members revolubly mounted in the inlet zone, a plate adjacent to the peripheral path of said members which cooperates therewith to perform a crushing operation, said plate being arranged to provide a space outside of the path of the ham-- mers which communicates peripherally with the outlet zone,-and means including cooperatin .revoluble and stationary impact bodies w ich are located in the outlet zone and are adapted to receive material from said space and pulverize the same.

20. A pulverizing apparatus comprising a casing having an inlet and an outlet, a rotor therein, sets of interfitting impact bodies on the rotor and easing arranged adjacent the outlet to pulverize material fed thereto, and means providing a pocket for receiving hard foreign bodies fed through the inlet which prevents such bodies from contacting with the interfitting impact bodies.

21. A pulverizing apparatus comprising a casing, a disk rotatably mounted therein and arranged to form two pulverizing zones connected around the periphery of the disk, hammers mounted in one zone to revolve with said disk, a grid adjacent to the peripheral path of the hammers and spaced from the casing wall to form an annular passage, said grid having small openings for the passage of pulverized material and providing a large opening for the escape of hard foreign bodies from the pulverizing zone, and means on the other side of the disk to pulverize finely the material introduced from the first zone through the peripheral passage to the same.

22. A pulverizing apparatus comprising a casing having an inlet and a centrally located outlet, a rotor therein arranged to form two zones connected by an annular passage, a set of revoluble hammers in the inlet zone, a plate adjacent to the peripheral path of the hammers which provides an opening for crushed material to escape to said passage, sets of interfitting stationary and revoluble impact bodies within the outlet zone arranged to pulverize the material as it passes against the centrifugal action thereof towardssaid outlet, and a fan arranged to pass a current of air from the inlet to the outlet.

23. A pulverizing apparatus comprising a casing having an inlet and an outlet, a shaft rotatably mounted therein, a fan on the shaft to propel air through the casing, a rotor on the shaft forming two connected zones, a set of interfitting impact bodies on the rotor and the casing adjacent to the outlet to pulverize the material fed thereto, impact members adjacent to the inlet which are revoluble with the shaft and a plate adjacent to the peripheral path of said members which is spaced from the casing wall and provides an opening permitting the passage of crushed material radially to said space and thence to the outlet zone.

24;. A pulverizing apparatus comprising a casing having an inlet and an outlet, a rotor therein arranged to form two connected zones, revoluble impact devices, and a plate adjacent to their peripheral path in the inlet zone to crush the material, interfitting stationary and revoluble pegs in the outlet zone to pulverize the material finely and a rejector device to prevent the escape of coarse particles through the outlet.

25. A pulverizing apparatus comprising a casing having an inlet and an outlet, means mea sa forming two connected pulverizing zones therein which are adjacent said inlet and outlet, means including revoluble impact members and a perforated grid in the inlet zone to crush the material preliminarily, means to move a current of air from the inlet to the outlet, revoluble impact members in the outlet zone to pulverize the material fed thereto and revoluble rej ector blades to prevent the escape of coarse material from the outlet zone.

' 26. A pulverizing apparatus comprising a casing having an inlet and an outlet, means to move a current of air .therethrough, means forming two connected pulverizing zones adjacent said inlet and outlet respectively, means including revoluble hammers in the inlet zone which will .crush the material preliminarily without receiving substantial injury from hard foreign bodies, revoluble impact members in the outlet zone to pulverize the same and a rejector device arranged to return coarse material which passes said mem bers for further treatment.

27. A pulverizing apparatus comprising a casing having an inlet and an outlet through which a current of air is conveyed, means forming two connected pulverizing zones, revoluble impact members in the inlet zone, means associated therewith for eliminating large foreign bodies, revoluble impact members in the second zone and a rejector device to return for further treatment such coarse material as passes said members.

28. A pulverizing apparatus comprising a casing having an inlet and a centrally located outlet, means for moving a current of air through the casing, means forming two pulverizing zones connected by an annular passage, means including revoluble hammers in the inlet zones which crushes the material and distributes it to said passage free from larr foreign bodies, sets of revoluble and station ary impact bodies in the outlet zone arranged to pulverize the material as it passes against the centrifugal force thereof towards the outlet and a rejector device arranged to re turn for further treatment coarse material which escapes to the outlet.

29. A pulverizing apparatus comprising a cylindrical casing divided on substantially a diameter so as to form two separable parts, means for connecting one part to the other, and a member mounted within the casing with its center line near the division plane of the casing parts, which has pulverizing bodies thereon, said member being normally stationary but capable of being revolved so that the pulverizing bodies may be readily replaced without disassembling the machine.

30. A pulverizing apparatus comprising a substantially cylindrical casing formed of two separable top and bottom portions, a rotor mounted in the two portions of the casing, impact bodies on the rotor, a normally stationary but movable ring mounted with the casingand impact bodies removably mounted on said ring, said parts being so constructed and arranged that when the casing top has been removed said ring-may be moved to present the bodies mounted thereonsuccessively in posi-' tion whereby they may be removed from the ring without disassembling the machine.

31. A pulverizing apparatus comprising a casing, means providing an inlet for the inm troduction of air and material to be pulverized to the casing, means providing a small centrally located outlet therefrom, revoluble im- 'pact bodies between the casingperiphery and the outlet to finely grind the material presented thereto, means forming a crushing zone adjacent to the inlet wherein the material may be crushed. preliminarily, and means associated therewith to prevent large foreign bodies which enter the crushing zone from passinito said impact bodies.

32. pulverizing apparatus comprising a casing having inlet and outlet openings on opposite sides thereof, pipes communicating with said openings for conducting air and the material to and from the casing, a rotor in the casing, impact bodies on the rotor adjacent to the outlet to pulverize material fed thereto, and heater arms adjacent to the inlet revoluble with the rotor and a plate adjacent'to the peripheral path of said arms,

which are arranged to crush the material pre- 1 liminarily and feed it to the impact bodies.

Signed at Worcester, Massachusetts, this 10th day of October, 1925.

v v R. SANFORD RILEY.

OLLISCN CRAIG;

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