US1621869A - Method of granulating dry materials - Google Patents

Description

1,621,869 March 22 1927' F. L. BRYANT V METHOD OF GRANULATING DRY MATERIALS L Filed July 12. 1924 ji cuzk Patented Mar. 22, 1927.

."umi so STATES FRANK L. BRYANT,

OF Q'OIIIET, ILLINOIS.

f Israel) or enauur nrma DRY MATERIALS.

Application filed Ju1y I2 The present invention relates to methods of pulverizing and reducing to fine powder form various dry granular materials which .are of such a nature that they cannot successfully be pulverized by abrasion or gnind-.

ing. Thus 'far the only successful method of reducing such material to the desired degree of finenessvconsists in imparting to'the inateriahim a flowing stream a succession of impact blows by which the particles-sare brok'en up and reduced in size without excessive heating, such as occurs. in grinding mills, which heating causes the material to cake and solidify, thus defeating the intended result. My present invention relates to a process of t reatment on theimpact prinr ciple. Heretofore, so far as-I am aware, in carrying outthis broad method'of reduction by impact, the material in a'fiowing stream 10 has been subjected successively to impact blows ofequal intensity. I have discovered that by subjecting the material to a succession of impact blows delivered with successively increasing force, a superior result is obtained and the'material is more perfectly and effectively brought to the desire pulverized form. I

The invention is capable of being carried Q out by various kinds and forms of apparatus; but, in order that one practical meansfor practicing the invention may be known 7 I have, in the accompanying drawing, dis- 3 closed a formof mill designed to carry out my improved method of pulverizing and grinding material whichforms the subject matter of an application filed by me on the 7th day of February, 1923', Serial No. 617 ,482 and referringto the drawing Fig. 1 is a vertical section; and Fig. 2 is an enlarged fragmentary view partly in elevation and partly in, vertical section of the flow controlling and impact me6hanism, showing the general course of the material passing therethrough.

shown comprises an inverted U-shaped frame 1 provided with ledges 2 on whichan annular support 3 is mounted. A casin '4 is mounted on the support 3- and is provi ed with afcover 5 havinga feed chute 6 and a v centr'alf aperture 7. ,tThedo'wer end of the casing 4 is entirely open and registers with the inner periphery of the su port 3, and to -the under side of the latter a ischarge chute 8 extends downwardly" and communicates with a pipe 9 through whichthe pulverized Referring to the drawing, the mill therein,

, 1924. Serial 1m. 725548.

' material is conveyed to" any desired place of delivery. t

The casing 4 comprises a plurality of cylindrical portions 10, 11 and 12 which infcreasein diameter successively, and preferably uniformly, toward, the lower *or dis-- charge end ofithe; casing. The internal cylindrical surface of each section of the casing is preferabl formed with longitudi- 6 nally extending ri es or teeth 13. V a,

' A housing 14 mounted ontop of'theframe 1 is provided with {suitable anti-friction bearings s'uchas 15, 16 and 17 and a second housing lfisecured to the under side of the to meinber of the frame is provided with suitable anti-friction bearings such as 19 vertically spaced from the previously men-.

tioned bearingsx' A shaft'QO is journaledin the several bearings by which'it is wholly supported, preferably by suspending it on one .of the bearings by a collar 21 secured to the shaft. The shaft may berot'ated by any suitable mechanism; that illustrated com; prising a belt. 22 engaging pulleys 23, 241 3 and 25, the latter being carried by a shaft, 26 journaled in bearings 27" in housings 28, the, shaft being also provided with a driving pulley 29'. The frame 1 is hollow and houses. most of the operating mechanism just de- '(s1cribedfso as to effectively protect it from ust.

a The shaft 20 projects through the opening 7 in the cover 5 downwardly into the casing 4. lVithin the casing a plurality of v discs 30, 31 and 32, spaced apart b blocks 33-, aretsecured to 'the shaft 20. T e discs "are positioned respectively in the' several cylindrical portions of the casing, and increase in diameter successively toward the lower discharge end of the casing, the diameters preferably increasing uniformly and preferably in proportion to the dianreters. of the cylindrical ortions of the casing. In the mill illustrated there is one disc inveach cylindrical portion. If .desiredftwo or more discs of the same diameter may b located in each cylindrical portion of the casing, in which case the successive grou s of discs will-be of increasings di ameter rom topflto I0 bottomof'the casing. I

A"plurality of heaters 34' are secured -in spaced relation around the periphery of each of the discs 30, 31'and 32, Preferably the 1 same number of beater-s will bemounted on Each discrandfltlle heaters of one'disc stag- Igered with relation to the heat rs of the next adjacent disc. Each'disc is of such diameter as to underlie the beater's of the preceding (lISC. Each beater is'preferably formed with a flange 35 by which it is secured to the disc as by a rivet 36. The heater projects substantially equal distances above the top side and below the bottom side of the disc.

In operation, the material in dry granular form is fed to the chamber through the feed hopper 6.- As the material falls on the first disc it is thrown outwardly by centrifugal force until it reaches the edge of the disc and drops by gravity into the rotary path of the heaters carried by the first disc. The impact ofthe beaters, delivered crosswise of the direction of flow of the material, breaks up andreduces the latter, which drops onto the succeeding disc, some of itbeing thrown I g in the rifiies or corrugations 13 in thel casing, by which the material is additionally impacted, .and prevented from whirling around the casing. When the material drops onto ,the second disc it is again thrown outwardly by centrifugal force and y then drops by gravity into the path of.

the heaters on .the second disc, and in this manner, progresses through the mill. .The peripheral speed of the heaters carried by 'the dis-r:- is successively greater, and, conse quently, as the material progressing through the mill becomes finer-and more difficult to reduce it is subjected to blows of correspondingly increasing force. It is important that the reducin process be carried out as rapidly as possi le so as to avoid the deleterious effect of heat thereon. A mill such as that described produces a strong air current flowing from'the feed end toward,

the discharge end of the casing, andthis current, aided by gravity, serves to carry the material through the impact chamber wit-l1 great rapidity, and also'to carry off such; eat as is generated. The apparatus described also provides forthe immediate discharge of the reduced material from the lower chamber so that it cannot pile '11 into contact with the lower disc and be Sub ected to the heat of friction which wouldvcause many materials to form asolid mass requi'r ing stoppage and clearing out ofthe mill,

,From theforegoing it,will readily be un derstood that the apparatus shown and dedry material,; such, for instance, as acid ph hate used in the preparation of com-' mercial baking powders. The pulverizing is accomplished mainly by the blows of the heaters against the material assing 'over the peripheral edges of the discs, and the casing is not a grinding element, but a mere retainer or restrainer of the material, with the rifiles or teeth, where employed,cooperating in a-measure with the' beaters in the impacting of the materiaL- As hereinabove' stated, the subjection of the material to a succession of impact blows delivered with successively increasing force at succes sive' stages (if the flow of the material, whereby the latteris reduced toa predetermined degree of fineness without attrition or excessive heating, constitutes the chief novel and 'most important-feature of the present method or process; and' the apparatus hereinabove described and shown in tpe drawing is well adaptedhto carry out his-method of treatment a though, manifestly, the same method iscapable of being caried out by many other and specifically practical means by which the'novel method of treatment may be carried into effect.

I claim 1. The method of granulating materials 'by impact without substantial attrition or excessive heating, which consists in placing all of the particles thereof in suspension andfeeding the same downwardly through successive annular granulating zones, and while in suspension imparting to them a succession of impact blows at different horizontal planes while constricting the"material 'to move in substantially a vertical path through the granulating zones, causlng said 'blows to be delivered with successively increasing force during the gravitation of said particles until the material is reduced toia substantially uniform degree of fineness, and

causing a substantially free passage of the material throughout the granulating zones and annular final discharge. Y

2. Theinethod of granulating materials by impact without substantial attrition'or excessive heating, which consists in placing all of the particles thereof in suspension and feeding the same downwardly through successive annular granulating zones whilesre straining the particles to move 1n substantially vertical paths, and whlle in suspension impart-'ingio them a succession of impact "blows during the passage of the material through the granulating zones and while the materials are gravitating downwardly, caus ing said blows to be delivered with successively increasing force during the gravita tion' of the partlcles through the successive granulating zones until the material is reduced to a substantially uniform degree of fineness, and causing a substantially. free passage of the material throughout the granulating zones and annular final discharge.

FRANK L. BRYANT.

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