US2127137A - Apparatus for treating finely divided powders - Google Patents

Description

Aug. 16, 1938. H. w. PRICE y 2,127,137

APPARATUS' FOR TREATING' FINEIlLlY DIVIDED POWDERS vFiled Jan. 17, 1934 vill/m11 /a Af #il ZZ/f ffii/(Hf fz Patented Aug. 16,1938

UNITED STATES PATENT oIfFic-l?.

APPARATUS FOR TREATING FINELY DIYIDED POWDERS i Howard vW. Price, Borger,

Tex., assignor, by

mesne assignments, to J. M. Huber Corporation, Borger, Tex:, a corporation olf-Delaware Application January 17, 1934, Serial N0.`706,909

' 3 Claims. (Cl..- 259.-3)

bonaceous blacks known as carbon black or channel gas black, lamp black and other' carbons manufactured-by the decomposition of carbonaceous gases and used for compounding with various substances such a's rubber compounds, peints land varnishes, printing inks, sound recording material and various wax and resinous pyroxylins.

A Well recognized difficulty in handling all of these line powders is that they sift through the Fcontainers used to confine them. Moreover, when packed in barrels or paper sacks, an excessive dusting occurs when the products are being used or 'mixed with other ingredients, and as a result the area surrounding the points or points of handling is lled with dust which settles on surrounding objects, contaminates other products, and pollutes the air which. those working with theproduct have to breathe.

Carbon black is illustrative of this type of material and oi the diieulties encountered in making and usingit. This product is particularly hard to handle due to the fact that it is a very light and finely divided material composed entirely of amorphous carbon particles and withoutany binder. As it comes from the decomposition housesand through various bolting and sifting apparatus, it has a weight of `only two to four pounds per cubic foot.

V Before this blackis packed into commercial containers, usually paper bags, it is customarily placed in suitable bins, having within them revolving shafts to Vwhich are attached blades or pins. In 'these bins the black is agitated or A 40 stirred to agglomerate the particles andto increase'their weight per cubic foot by disassociating from the particles the air and gases which have. become entrained in them.

It is not always desirable, however, to' carry out this agitation to a point `where the black exceeds a weight from twelve to fteen pounds per cubic foot as further compressing by this means is likely to eliminate some of its characteristics of easy incorporation in certain oils and varnishes such as are used in the paint-.and ink trades. However, for the pu'rpose of compoundf ing with other more viscous materials such 'as' rubber, where large 4quantities are used, it has been' customary to compressthe black further- '-.55 by means of heavy' hydraulic or mechanical presses to a. state where its weight is from twenty to thirty' pounds per cubic foot. This briquet.-` tig process is of advantage to prevent sifting and dusting in handling, as well as to reduce the amount oi storage space required, although it in- 5 volves'a number of disadvantages as will hereinafter appear,

Practically all modes of handling black require a preliminary bin agitation such as that briefly referred to above. This method of pro- 10 longed stirring in order to eliminate entrained air and gases is almost uniformly used as a preliminary procedure for any process in which the carbon black particles are mechanically treated.

It has also been found that this treatment hasl5 lits limitations, for if agitation be carried to a point Where the black is reduced to an apparent density of more than fifteen pounds per :cubic foot it is necessary to use a relatively large amount of ppwer and to run thel risk of rire by 20 reason of the great internal friction set up between the black particles and between the black and the agitation blades or the sides of the bins. Further to reduce the density of the black to facilitate easier handling, to reduce storage space, 25

and to produce a firmer agglomeration of the particles to minimize dusting, several methods are in use. l l One such method is to subiect'the carbon black Eto multi-directional pressure by violently agitat- 30 ing and compressing lt, thereby causing the par# ticles to be hammered into aggregates of spherical form. This is in reality an extension ofthe bin agitation principle and although the resultant product may sometimes vbe found to be sat- 35 isfactory, the process requires high speed machinery and-a large amount of power, thus making it expensive, particularly as only limited quantities of carbon black can be treated at one time in the apparatus necessitated by this procedure. 40 The clearances between the various moving parts of the apparatus used iu this treatment, as well as other conditions, require extremely ne atiju'stment and control whichare obtained and maintained with difficulty, and unless these var'- /45 ious conditions are properly regulated, the aggregates are likely to vloecomebroken up and sheared,'with little or no benefit having been derived from the treatment. Moreover, the high speeds necessary properlyfto agitate the carbon black particles by this method arelikely tocausef-a an exssivaf'rmnonn neat to be'sevelped. 1n the carbon blackcharge, thus creating the danger of losses bym-e.

f ,Aspreviousiy-ii1d'icatedit has also beencomi mon practice in the art to utilize various means in order to apply heavy pressures to aggregates or carbon black in order to compress them. This procedure, although it does not overcome the disadvantages of handling the dusty carbon black preparatory to compression, does reduce the volume of the black as well as its tendency subsequently to dust, and carbon black in this compacted condition is commercially sold, hav.

ing a density close to twenty-five vpounds per cubic foot. Often' the black is compressed in bags or other containers which become wrinkled and crimped during the pressure treatment, thus trapping a considerable quantity of carbon black in the wrinkles, and this entrapped black can only be removed by violent shaking and then only at the expense of a cloud of dust. It is obvious 4that the application of heavy pressures involves heavy and expensive machinery, a large amount of power,-increased expense and delay in preparing the product for shipment, while the product is very likely to be caked so hard that it is diilicult to disperse or to mix it with other' material.

Another mechanical procedure used to render carbon black more dense and capable of being more easily handled is the application of pressure by passing it through the rollers`of a Wheatley press. This procedure is carried out after an initial bin agitation which brings the product down to a density of from twelve to fteen pounds filed Dec. 21, 1933, II have disclosed and claimed a.

vper cubic foot, and involves compressing the black in a screw conveyor and delivering it to and passing it through several pairs of rollers :capable vof pressing andconsolidating it. Such-a procedure, although possessing the advantage of continuity oi' treatment, produces hard ilakes which do not readily break down, as on a rubber mill, and which must be 4forced through a screen to break the flakes apart again, and this usually involves the production of a considerable quantity oi!r the same line dust which was originally sought to be avoided. Moreover, the amount of black which can be passed through one machine of this type is` limited and production is retarded to this extent.

There have been other'methods suggested of reducing the apparent density and dustiness of carbon black, notably those involving the midl-A tion of tarry binders and by wetting the charge with a suitable agent or agents. These methods, however, are not strictly mechanical in nature and, therefore, will not be discussed in detail.

In my co-pending application Serial No, 70.3,'402

continuous treatment contrasting sharply with previously proposed methods of mechanically treating carbon black in order to retain its desirable characteristics vbut to eliminate its undesirable ones. The present invention is directed to an apparatus.- by` means of which .this novel method may be accomplished, with the elimination of the disadvantages inherent in,previously 6.5; known apparatus, necessitated by the processes paratus of the present invention is applicable to which they were required to carry out. The apthe treatment of various kinds and forms of finely d ivided material although it is described in this specification in connection with the treatment of carbon black for purposes of illustration.

Objects of the invention will be seento include the provision of an apparatus which circumvents the difllculties heretofore faced in the aggregation of nely Adivided material such as carbon fects the agglomeration of the particles.

which it is ordinarily used.

and conveyors, and tobe transported intank cars or tank trucks Without material disintegration.

I have discovered that it is possible to change inely divided vmaterial such as carbon black to a dense, free-flowing, non-dusting state of agglomeration by mechanical means without placing it in or passing it through presses and without preliminary or violent agitation. This may be done by an apparatus which subjects the material to a continuous tumbling agitation by advancing the black through a predetermined course within a revolving-drum or drums in certain of which are included a series ofv relatively light, free rollers which continue to eliminate the entrained gases and air. After4 being subjected to this treatment the particles become agglomerated into a product of the desired density. While carbon black may be previously agitated in the regular way before being subjected to treatment, it may also be taken just as it comes from the bolting or sifting apparatusA Without initially stirring. or 4agitating it inbins,l as explained above, where-heretofore it was required to be brought to a density of approximately twelve to fifteen pounds per cubic foot beforeit was ready for further processing. The black is subjected to a progressive moderate pressing, rolling and tumbling of the particles which effects a continuous gentle agitation by virtue of which the black can be processed continuously and brought directly to an apparent density of twenty-five or more pounds per cubic foot. This agitation may be seen to involve a treatment of the particles in an unconflned state, Without the.use of heavy confining pressure, and the treatment ef- They are subsequently separated into coherent polyhedral agglomerates of a size that can be handled without dusting. The process is continu ousand, therefore, well .adapted to quantity production, and separate preliminary or accessory treatments and their accompanying cost, equipment and labor are unnecessary. The product is of a substantially uniform standard of quality and well adapted to flow without dusting; it is compact and easily handled without substantial loss by dispersion'in air, and is readily dispersible or miscible with the types of ingredients with Referring to the drawing, Fig. 1 is a side eievation, partly in section, of the apparatus of the present invention; Fig. 2 is Aa section taken through line 2-.2 vof Fig. 1 with the conveyor -structure omitted; and Fig. 3 is a detail of a preferred type ot connection between the cornpai'tments of the revolving drum of Fig. 1.

Briefly described, the apparatus consists of a revolving drum III provided with compartments delivered for,tumbling and agitation.

pass slowly from one compartment to another and finally emerge. from the.1ast drum I6 in a substantially uniformstate of agglomeration.

The compartments in drum III, which is pref,-

. erably of'iron or steel,.are formed by circular iron or steel plates I8, I9, 26,21 and 22, secured betweencylindrical members 24 as by brackets 25 and 26. The preferred means for securing these members together, in order to ensure a' smooth interior, is indicated in Fig. 3, the brackets 25 and 26 being welded to the cylinders 24 as at 29 and fastened together by turning nut 28 on bolt 21. By welding` the brackets in proper position,

one of them is made to overlap the adjacent cirf cular plate, such as is, indicated at I9, and also to allow the sections 24 to be drawn tightly against the plate to provide a tight and rigid con#- nection.

At the feeding end of the machine, end plate n of drum Ill has bolted thereto a hanged cylinder 30 into which is extended the delivery end of a screw conveyor 3 I. The vconveyor housing is supported by suitable supports' 32 secured to any suitable framework. To the'housing o! the screw conveyor is xed member 33 extending around the hanged cylinder 30 and provided-on its'inner.

' face with packing material 34l Isuch as graphited fabric or cord in order to seal the joint and prevent the treated material from dusting" there-V through. f

The shaft of the screw 36 of the conveyor, may be provided with a pulley 31 driven by belt On frictionally to contact against tires 42 secured to the outersurtaceoi' each cylin r 24. Shaft 40 is journaled in bearings 43 (see g. 2) secured to standards 44 on base B. The shaft'4ll is driven by' any suitable -source of power M .applied through reduction gears R.

The drum structure is also carried by standards Y.

44 which carry bearings 45 for holding shafts 41 which in turn carry a number of rollers 46 upon which the drum assembly I rests and rotates on being driven through wheels 4I and tires 42. This supporting structure is clearly seen in Fig. 2. It desired, the shafts 46 and wheels 4| may be omitted and one set of rollers 46 arranged to impart rotation to the drum.

The exit end of the (1mmA assembly is closed by plate 23 to which is secured a gland 48 containing'packing 49. This packing is pressed against I another flanged cylinder I! secured to a iixed member 5| of the framework of the machine. Member 50 extends into the last compartment I6 of the drum assembly and member'BI. is provided with an opening 52 to allow the aggregates of material to pass through it.

It will be seen that the above described conlstruction provides va sealed joint` at thev exit or. discharge end, as well as the'feeding'end of the tent which will prevent'the treated material.

from. owing too quickly from theirI zone of action. The partitions may, therefore, be made so that relatively large openings 53,54, etc. are provided.

In the first two compartments relatively long light rollers 58 and 59 of wood, rubber surfaced metallor other suitable material, are provided so that they roll about `the inner surfaces of the cylinder 24 as they rotate. JBaffies 60 provided with apertures 6I to prevent the treated material from clogging the apparatus, may be secured in place by rods 62 in turn secured tothe plates I1, I8, and I9. These baiiles tend to 'prevent dust, which is presentl in large quantities in the rst two drums, from iiying into the otherdrums. In some cases itfmay be found desirable to dispensewith these'bafiies 80.

The compartment I3 may be provided with a for instance, a screen of one-half inch mesh.

. 'I'his` roller may, however, be replaced by a solid roller of the type described for compartments II compartments I4, I5- and I6 contain no vrollers but are lined with wire screen material 64 of appropriate` size, one-half inch mesh` being satisfactory in' the treatment of carbon black..

These screen linings may be omitted if desired.

Directly underneath the exit end of the ma- .chine there may be provided shaker screens 65 A and 66 sliding in suitable guides (not shown) vwire screen roller Iii! having, suitable openings,

tween drums 'I2 and 13, the later being positioned over hopper 35 of the screw conveyor. The belt may be driven from any suitable source of power applie'dlto the shafts of drum 'I2 or 13. Y

. The scr ens 65 and 66 may be dispensed'with by propei regulation of the conditions of the process.

. f In operation, power issupplied todrive shaft l4|| and4 nely divided material suchascarbon black is fed from chute 14 into hopper 35 and conveyed by screw 36 through member' 30 and into the iirstcompartment II of theapparatus.

Shaft 4||` drives the screw conveyor through pulleys 39 and 3,1 and belt 36, and also causes the drum assembly to rotate by reason of wheels 4I 'rotating against tires 42. 'Ihe drum assembly is rotated rather slowly, say l0 R. P. M., so that the material is tumbled and thereby agitated and agglomerated in the various compartments and passes slowly from one to thev other until the last one is reached.

In giving a. specific angular speed of 10 R. P. MI., it should be remembered that this is illustrative merely,.and is a satisfactory rspeed of operation when treating carbon black. The speed the conditions of such case require. In the main, the principle to be observed is that the drums or compartments, with rollers removed, should not rotate so fast that the material is carried upwardly and caused to pour back into the center of the treated mass, but should be only fast enough so that it will roll down the inner surface o1' the drums and. thus be `subjected tothe gentle tumbling action sought to be imparted.

The supply oi treated material is preferably controlled so that each compartment is somewhat iess than one-half full. 0i course, the marequired inany given case should be adjusted as chine might 'be operated with the compartments more than hali' full, or considerably less than 75 half full, but in order to-.operate atinaximum efllcincy consistent with maximum rate of flow, the operation should vbe carried out as indicated.

In general, the effect of the rollers in the first l two or three compartments isy to give a gentle rolling pressure bywhich entrained air and gases may be eliminated and the density of the black increased. The inner surfaces of compartments Il, I5 and i6 give a gentle tumbling action and, facilitate the. formation of granules. As the drum assembly rotates,` the particles are first made more dense and afterwards collect in substantially uniform agglomerates within the desired range of sizes, by reason of the continuous gentle pressing and rolling treatment and tumbling action, to which they have been subjected, and-theygradually pass from chamber to chamberjuntil they emerge from` cylinder 50 through opening 52 and drop down on chute leading to a conveyor 15 for transmission yto the packing point, or upon the shaker screens 65 and 66. AAt this point the whole mass has become agglomerated into aggregates which are quite compact and which possess considerable uniformity in size. When screening is desired, the screening apparatus is operated through shaft 40 by clutch and gears' 19, worm 16 and gear 11. This operates the eccentric 68 and causes the screen to reciprocate. The screens are vof, predetermined mesh and for'carbon blackl may state that a -very desirable product may be obtained by mak.

ing the screen 65 of 20 mesh and screen 66 of 65 mesh. Particles smaller than mesh will drop through screen 65 and particles smaller than 65I mesh pass through screen 66 and drop down in chute l0. The particles which failto drop through screen 65 are undesirable because they are too large and they are removed at short intervals during the operation of the machine and led to conveyor 1l. If desired, the screen 65 may be tilted to cause these particles to fall directly upon conveyor 1l. Conveyor 'Il brings 'them to the other end of the machine and drops them in hopper 35 where they are again put through the apparatus in order to bring them down to the .required size. The particles which come through the screen 66 a're too small and, as indicated in Fig. 1, they are dropped to the chute 10 and delivered to the conveyor 1| where they, together with the larger particles, are brought -to the feeding end of the apparatus and again put through it in order to build them up into more desired agglomerates The particles which re main on the screen 66 are of the desired size anoin the instance illustrated will .be of a size ranging from 20 to 65 mesh. vThese are collected on the conveyor 'l5 and brought to fa suitable packing and shipping station. Screen 66 may be tilted to facilitate the passage of these agglomv erated particles to conveyor 15.

In the case of carbon black, I have discovered that by subjecting the nely divided material to a treatment in the above described apparatus, the f particles between 20 and 65 mesh comprise a substantial proportion of the total amount and as these are of a size eminently suitable forl the purposes in mind it is apparent that-the apparatus is very eiilcient in achieving its purpose.

In adapting the apparatus for the treatment of a particular material, it should be observed that the number of drums or compartments and the angular Speed thereof are factors determinative of the uniformity of thesize of the granular end product and, therefore, should be considered in determining the necessity for screens for selective separation. The weight of the rollers in the ilrst two or more drums is, on the other hand, determinative of the density of the product, and by proper choice of rollers the desired number of pounds per cubic foot of end product may be obtained.

It may be pointed out also that instrumentalities shown in thedrawing and referred to above in this specification are illustrative merely of a preferred embodiment ofy the invention. It will be understood, however, that the baiiles 50 in compartments I l and I2 of the device, while desirable, may beeliminated. Any form of con-` veyor may of course, he used instead of those shown at 1i and l5. Y

yWhat I claim is:

1.- An agglomeratlng apparatus comprising in combination. a rotatable drum divided into cylindrical compartments longitudinally thereof by partitions, means for feeding finely divided solid material into the first compartment, central openings in the partitions whereby the material supplied to the first compartment is allowed to overiiow into the next and successive compartments from one end of the drum to the other upon rotation thereof, and a light free roller within each of a predetermined number of the 'rst of said compartments also operable upon rotation of said drum, the subsequent compart-I material into the first compartment, central openings in the partitions whereby the material supplied to the first compartment is allowed to overflow into thel next and successive compartments from one end of the drum to the other upon rotation thereof, and a light free roller within each of a predetermined number-of, the first of said compartments also operable upon rotation of said drum, the subsequent compartments being free of rollers, and a discharge opening in the end wall of the last compartment.

3. An apparatus for agglomerating carbon black comprising a rotatable drum, a plurality of members disposed within the drum transversely thereof forming partitions therein dividing the drum into sections, a plurality of light free roll- 4ers each disposed within a separate predetermined section at one end of said drum sections yat the other end of the 'drum being free from HOWARD W. PRICE.

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