US 2213056 A
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Description (OCR text may contain errors)
Aug. 2'7, 19409 R. w. SKOOG ET AL APPARATUS FOR TREATING DRY FLOCCULENT POWDERS Filed April 29, 1938 M @4 9 jzTTbkNEi Patented Aug. 27, 1940 I UNITED ,STATES APPARATUS FOR TREATING nmz FLOCGULENT POWDERS Robert W. Skoog and Thomas J. Bradford,
Burger, Tex., assignors to United Carbon Company, Inc., Charleston, W. Va., a corporation of Delaware Application April 29, 1938, Serial No. 205,140
-. q 3 Claims.
The present invention relates to an apparatus for treating dry flocculent powders for the purpose of forming substantially dustless agglomerates therefrom. One field to which the present invention is particularly applicable is the manufacture of the so-called "dustless carbon black in accordance with the disclosures of the copending application of Hilding Hanson and Robert W. Skoog, Ser. No. 205,139, filed April 29, 1938.
It is a principal object of the present invention to provide an apparatus for treating dry flocculent powders which will impart to a wetted mass of such powders a definite size and shape without destroying the identity of the individual particles of the powder.
It is a further object of the present invention to provide an apparatus for treating dry flocculent powders to form substantially dustless agglomerates thereof,the apparatus being particularly adapted for use in continuous processes for the formation of small substantially spherical agglomerates of the flocculent material, part of which is wetted by a liquid wetting agent and part of which is utilized in its dry state.
Another object of the present invention is to provide an apparatus for treating finely divided fiocculent powders to form composite wet-dry agglomerates of self-sustaining forms capable of ready and uniform dispersion in a selected dispersion medium, the agglomerates occupying a decreased space and being more readily shipped, stored and handled than the unagglomerated flocculent powder, the novel apparatus herein disclosed permitting simplification of controls and lowered fuel requirements to dry the agglomerates, thus possessing many features of commercial advantage over the apparatus heretoforc known in the art.
A further object of the present invention is to provide an improved apparatus for treating flocculent powders to form graular particles generally spherical in shape, the particles being nonadherent and possessing suflicient density to resist ready displacement in the air and of such shapes and strengths as to resist crushing in normal handling and shipping, while possessing a readily frangible structure which permits ready breaking of the particles to make available the discrete individual particles of the original powder for dispersion in a dispersion medium.
Other objects of this invention will appear in the following description and appendedclaims, reference being had to the accompanying drawing 5 forming a part of this specification, wherein like reference characters designate corresponding parts in the several views.
Fig. l is a diagrammatic view of one form of apparatus embodying the present invention.
Fig. 2 is a side elevation with parts broken away 6 showing the interior construction of a preferred form of device embodying the present invention.
Fig. 3 is a sectional view taken substantially on the line 3-3 of Fig. 2 looking in the direction of the arrows.
Fig. 4 is a cross sectional view taken substantially on the line 4-4 of Fig. 2 looking in the direction of the arrows.
Fig. 5 is an elevation with parts broken away of a modified form of apparatus embodying the 5 present invention.
Before explaining in detail the present invention it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawing, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation, and it is not intended to limit the invention claimed herein beyond the requirements of the prior art.
The present invention is intended for use in processes wherein dry flocculent powders are formed into substantially dustless' agglomerates. Inthe preferred embodiment of the invention herein disclosed by way of example but not of limitation, the apparatus is particularly designed for use in a so-called wet process or with a socalled wet and dry process. In either of the processes the agglomerates are initially formed from a plastic mass of the dry flocculent powder which has been wetted with a suitable wetting agent. Such a wetting agent must be non-redo active with the dry powder and must not effect any appreciable change in the chemical or physical condition of the individual particles of the treated powder. In the instance where carbon black is the dry powder to be treated, water is a desirable wetting agent.
As shown in the diagrammatic view of Fig. 1 the apparatus consists essentially of a cylindrical drum it which is mounted on a plurality of driving rollers II which support the casing l0 and impart a rotary movement thereto. Since many methods are known for imparting such rotarymotion to a drum it is to be understood that any suitable type of rotating mechanism may be employed within the scope of the present invention.
The dry flocculent powder is continuously charged into a hopper |2 from any suitable source of such powder and feeds through a conduit I3 to the interior of the drum H]. In the case where carbon black is the powder to be treated, it maybe fed to the hopper or directly to the drum by a conveyor leading from the burner house. The wetting agent is supplied to the interior of the drum I0 through the conduit l4 and its flow is controlled by the valve I5. When a dry flocculent powder, such for example as carbon black, is charged into the hopper I2 and fed to the interior of the cylindrical chamber Ill, water is fed through the conduit 4. The flow of the carbon black and of the water is so regulated that substantially equal amounts by weight of carbon black and water are fed into the cylinder I0. As the wetted carbon black traverses the length of the cylinder I0 it is formed into a plurality of separate particles which are substantially spherical in Shape and these particles are discharged through the discharge duct l6 from which they may be conveyed by the conveyor H .to the desired type of drying apparatus wherein the moisture content of the particles is reduced.
If desired, the particles discharged from the conduit l6 may be fed into a hopper of another device identical to that which is described, wherein the wetted black particles will be charged into the hopper |2 and a dry flocculent powder will be introduced to the interior of the drum l0 from the other hopper. The admixed wetted carbon black particles and the dry flocculent powder will then be acted upon by the apparatus and will be discharged as a plurality of small spherical agglomerates through the discharge duct |B from which such wet and dry agglomerates may be carried to any suitable drying device for removing the remaining moisture from the particles. In such an operation it is desirable that the mixing members he so arranged that a different direction of rotary motion is imparted to the particles in the separate members.
The interior of the drum ll] is shown in Figs. 2, 3 and 4. As there shown, a central shaft 20 extends lengthwise of the drum and is provided with a plurality of extending pins or arms 2| rigidly secured thereto. The arms 2| are arranged longitudinally of the shaft with their centers lying on a substantially helical line extending from end to end around the shaft. Successive arms are arranged at an angle of approximately to each other. By this arrangement, the arms 2| cause the material worked upon to advance progressively through the drum from the inlet to the discharge opening. During this travel through the drum, the material is formed into spherical shaped agglomerates due to the action of the arms 2| and the action of the plurality of pins or arms 22 which are secured to the interior of the drum l0 and extend inwardly thereof on radial lines in staggered circumferential courses adjacent the paths of the arms 2| and lengthwise of the drum. This arrangement is clearly shown in Figs. 3 and 4. The shaft 20 may be a stationary shaft or the shaft may be power driven. In either instance the drum Ill revolves about the center line of the shaft as an axis. The shaft 20 may be power driven in the same direction of rotation as the drum ID, in which instance it is preferable that the speeds of rotation of the shaft and of the drum should be different. It is, however, preferable that the shaft 20 revolve in the opposite direction of the direction of rotation of the drum I0 and that the shaft 20 revolve at a. different speed than the speed of revolution of the drum I0.
In a preferred embodiment of the invention the drum It! was constructed as a cylindrical shell of approximately 30 inches in diameter and 10 feet in length. The pins 22 which were secured to the shell each were approximately 10 inches long and of approximately inch in diameter. The courses of the pins were spaced approximately 2% inches apart and extended circumferentially of the shell. The pins or arms 2| on the shaft 20 in this embodiment of the invention were each approximately 14 inches long and inch in diameter. The pins were located spirally of the shaft 20, in staggered relation to each other, and were spaced approximately 2 inches between centers. As shown in Fig. 2 the pins 2| extend radially outward of the shaft 20 and are placed at an angle of approximately 90 to the succeeding or preceding pin or arm 2|. This construction operating on wetted carbon black produced a mass of substantially spherical pellets which were progressively advanced through the drum and discharged through the discharge .opening communicating with the conduit I6.
A modified form of apparatus is shown in Fig. 5. As there shown the mixing apparatus comprises a cylindrical drum 30 which is rotatably mounted on a plurality of supporting and driving roller members 32. A bafile member 33 is secured to the inside of the drum 30 and separates the drum into a wet mixing portion 34 and a dry mixing portion 35. The wet mixing portion 34 is formed substantially as shown in Fig. 2 with a plurality of pins 36 secured to the shell 30 and a plurality of pins 37 secured to a hollow shaft member 38. In this instance the shaft member 38 is preferably stationary and has an open conduit portion 39 which extends through the baflle 33 and discharges into the portion 35.
The operation of this apparatus may be substantially as follows:
A conveyor 40 discharges a dry flocculent powder into the interior of the mixing portion 34 of the drum 30. A suitable wetting agent is introduced into the interior of the drum 3!] through a conduit 42. The flow of wetting agent is regulated by the valve 43. The rotation of the drum 3!] causes the wetting agent and the dry agglomerated powder to be thoroughly mixed and causes the mass to assume the form of small wet spherical agglomerates during the course of travel of the mass transversely of the mixing portion 34 of the drum 30. The wet agglomerated spherical particles are discharged through an opening 44 in the battle 33 and drop into the dry agglomerating section 35. A dry flocculent powder as for example carbon black is fed through the interior of the hollow shaft 38 and is discharged through the discharge opening 39 where it falls into the agglomerating section 35. The wet particles and the dry flocculent powder are thoroughly admixed and are subjected to a continuous agitation while being subjected to drying. This action is that of a rotary tumbling device. The rotation of the drum 30 causes the dry powder to adhere to the wet particles and to absorb some of the moisture from the wet pellets so that the pellets grow in size without materially increasing the moisture content of the larger agglomerates. The combined wet and dry said courses, a baffle secured in said drum at the I agglomerated particles arev then discharged through a discharge duct 45 after having traversed the entire length of the cylindrical shell 30.
' ing a specific weight of approximately 24 lbs. per Y The particles are then conveyed to a suitable drier where the moisture content is further reduced.
As disclosed inthe co-pending application of Robert W. Skoog and Hilding Hanson, Ser. No. 205,139, a typical example of a product which was manufactured in the device' herein shown using the wet and dry method of agglomerating carbon black as therein disclosed, consisted of small spherical particles of dustless carbon black havthe product on standard testing screens it, was
found that approximately 97.69% was retained on a 100 mesh screen, approximately 1.47% was retained 'on a 200 mesh screen and approximately 0.38% was retained on a 300 mesh screen. The balance passed through the screen and was recovered from the pan.
The-dried product possesses a novel structure due to the method of forming the particle by the combined wet and dry agglomeratlng action here disclosed. The nucleus of the particles formed by the wet agglomerating action is in general more densely compacted than is the shell formed by the agglomerated dry powders. The essentially amorphous nature of the shell permits ready dryingof the interior of the agglomerated particles and is also readily broken up to permit dispersion of the individual particles into a selected dispersion medium. The formation of the wet-dry agglomerates as herein disclosed is more rapid than either a whblly wet or a wholly dry agglomeratlng end of said wet agglomerating section, a dry agglomerating section communicating with said wet agglomerating section and communicating with the discharge opening in said hollow shaft, said dry agglomerating section being adapted to admix dry flocculent powders with the wet agglomerates from said first named section while maintaining said agglomerates and dry powder in intimate rolling contact with each other,
2. An apparatus particularly adapted to form substantially dustless agglomerates of dry floccu lent powders, said apparatus comprising a rotatable drum having a wet agglomerating section and a dry agglomerating section, said wet aggiomerating section having a series of inwardly extending radial pins arranged in circumferential courses, means for feeding said powders into said drum, means for feeding a wetting agent into said drum, a shaft extending longitudinally of said drum and having radial arms extending between adjacent courses of pins in said drum and adapted to form said powders into wetted substantially spherical agglomerates, said dry agglomerating section comprising a tumbling section having an inlet communicating directly with said wet agglomerating section for receiving said wetted agglomerates therefrom, and an inlet for dry flocculent powders, said dry agglomerating section being adapted to admix said wetted agglomerates with said dry powders and to form substantially dustless agglomerates therefrom.
'3. An apparatus for forming substantially spherical shaped agglomerates of flocculent powders comprising a cylindrical drum containing a wet agglomerating section adapted to form wetted nuclei of the agglomerated powders and comprising a series of radial pins secured to a forward section of said drum and extending inwardly thereof in circumferential courses, means for feeding said powders into said drum, means for feeding a wetting agent into saidv drum, a shaft having radially extending arms arranged spirally of the shaft and extending between said courses of pins on the drum, an annular bame secured in said drum at the end of said wet agglomerating section and having a central opening therei a dry agglomerating section adapted to admix dry flocculent powder with the wet glomerated nuclei and communicating with said wet agglomeratlng section through said central opening in said annular baffle, and an inlet in said dry agglomerating section for introducing dry 'flocculent powder into said section.
ROBERT W. SKOOG. THOMAS J. BRADFORD.