US3751543A - Pelletizing process - Google Patents

Pelletizing process Download PDF

Info

Publication number
US3751543A
US3751543A US00156629A US3751543DA US3751543A US 3751543 A US3751543 A US 3751543A US 00156629 A US00156629 A US 00156629A US 3751543D A US3751543D A US 3751543DA US 3751543 A US3751543 A US 3751543A
Authority
US
United States
Prior art keywords
pelletizing
powder
zone
wall
members
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00156629A
Other languages
English (en)
Inventor
P Hare
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cities Service Co
Original Assignee
Cities Service Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Cities Service Co filed Critical Cities Service Co
Application granted granted Critical
Publication of US3751543A publication Critical patent/US3751543A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
    • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
    • C09C1/44—Carbon
    • C09C1/48—Carbon black
    • C09C1/56—Treatment of carbon black ; Purification
    • C09C1/58—Agglomerating, pelleting, or the like by wet methods
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/19—Oil-absorption capacity, e.g. DBP values

Definitions

  • the present invention pertains to an improved process for pelletizing powders by wetting the powder with a liquid pelletizing agent and agitating the resulting wetted powder mass to form the pellets.
  • the present invention resides in the general area of agitating wetted powder to form pellets by means of a pelletizer having an elongated pelletizing zone, a rotatable shaft which extends through the zone, and a multiplicity of agitating members fixed at spaced intervals along the length of the shaft and which extend radially outward therehom.
  • a wetted powder is thus agitated and pelletized while also being advanced from the powder inlet of the pelletizing zone to the pellet outlet thereof.
  • the resulting pellets are dried after formation to remove the pelletizing liquid.
  • the second pelletizing chamber is provided with three parallel shafts having agitating members.
  • the agitating 3,75l,5543 Patented Aug. 7, 1973 members of each shaft are arranged to move into and out of interdigitating relationship with agitating members of an adjacent shaft upon rotation of the shafts. Agitation of the wet pellets is thus accomplished by interdigitation of the members; i.e. the mass of pellets is very .forcefully cut by closely spaced members which move in opposite directions upon counterwise rotation of the shafts.
  • pelletization rate, density, and the amount of pelletizing liquid required are a function of the amount of work delivered to the wetted powder mass during agitation, i.e. as the work is increased the pellet .formation rate and density increase and the required amount of pelletizing liquid decreases.
  • Another object is to provide a process of increasing the formation rate of pellets of a powder.
  • Still another object is to provide a process to produce higher density pellets of a powder.
  • Yet another object is to provide a process to reduce the amount of pelletizing liquid required to wet pelletize a powder.
  • a wetted mass of powder is pelletized by agitation in an elongated agitating zone having two axially extending rotatable shafts therein, each of the shafts being equipped with elongated agitating members which interdigitate within a region of the pelletizing zone toward the center line thereof.
  • the pelletizing zone has a curved, longitudinally extending periphery which is proximal to the tip-ends of agitating members which are not interdigitated.
  • the wetted powder mass is caused to swirl around the peripheral region of the pelletizing zone, and agitating members which are not interdigitated are moved through the wetted powder in this peripheral region. .
  • the wetted powder is discharged from the peripheral region and is passed into the more central region of the zone wherein the agitating members are interdigitating.
  • the wetted powder is then discharged from this central region of the pelletizing zone and is returned to the peripheral region.
  • More effective pelletization thus results from coupling the work available from the interdigitating agitating members with that which results from moving agitating members which are not interdigitated through a resisting mass of wetted powder which lies against the wall of the pelletizing zone.
  • FIG. 1 is a top view, partly in section, of a pelletizing apparatus, for forming pellets in accordance with the present invention.
  • FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1 and show agitating members of each shaft in fllfinterdigitating relationship with members of the other s a t.
  • FIG. 3 is the same as FIG. 2 except for showing the agitating members of each shaft just after they have moved out of interdigitating relationship, this being caused by rotating each shaft through 45 degrees from the positions shown in FIG. 2.
  • FIG. 4 is a side view, taken along line 4 4 of FIG. l.
  • FIG. 5 is a side view of the pelletizer of FIG. 1, but equipped with an access panel, or door, in the wall of the pelletizer conduit, the door being shown in the closed position.
  • FIG. 6 is an end view from the left of the pelletizer of FIG. 5 showing the access door in an open position.
  • the pelletizer comprises an elongated pelletizing zone, generally represented at 1, which is bounded by a pelletizing conduit 2. having the cross-sectional configuration of two overlapping circles having the overextending segment of each circle removed, e.g. FIG. 2 or 3, and thus providing communication between the two partially cylindrical bilateral halves of the pelletizing zone over its full length.
  • a pelletizing conduit i.e. each partial cylinder
  • Each shaft extends axially through the pelletizing zone along the axis of the partial cylinders.
  • the shafts are supported by bearings 4 mounted on end-closure plates 5 for the pelletizer conduit.
  • Each shaft is provided with a multiplicity of elongated agitating members 6a and 6b, hereinafter referred to as pins, which are xed at spaced intervals along the length of the shaft and which extend radially outward therefrom.
  • the lateral spacing of the parallel shafts and the length of the pins is such that the pins overlap each other upon rotation of the shafts.
  • the longitudinal spacing of the pins along one shaft is staggered with respect to the spacing on the other, so that the pins do not collide upon rotation of the shafts but rather clear each other and thus effect interdigitation of the pins of one shaft with the pins of the other.
  • Each shaft is equipped with a variable-speed drive unit, generally represented at 7a and 7b consisting of an electric motor 8 and a speed reducer 9.
  • the pelletizing zone has an inlet 10 toward one end for the introduction of powder to be pelletized and an outlet 11 toward the other end for the removal of pellets.
  • a liquid supply conduit 12 extends through the conduit 2 for introducing a liquid pelletizing medium into the pelletizing zone.
  • Two such conduits can be employed, as shown in FIG. 6, for introducing liquid into each partial cylinder of the pelletizing conduit.
  • the method and means described in U.S. Pat. 3,535,412 is preferred for injecting the liquid longitudinally into the pelletizing zone and mixing it with the powder therein.
  • the pelletizer can he provided with a panel, or door, which provides ready access to the pelletizing zone for inspection, cleaning, and replacement or repair of the pins.
  • FIGS. 5 and 6 show the pelletizer equipped with a door 13, which is in fact a removable section of the conduit wall 2, but equipped with anges 14a and 14b so that it can be provided with a seal and fastened in place.
  • the door is unfastened and is then removed using handles 15. More conveniently, however, the door can be provided with a hinge 16 so that the pelletizer can be more easily opened and closed.
  • powder and a liquid pelletizing medium are fed into the pelletizer at predetermined rates through the powder inlet 10 and the liquid conduit 12, respectively.
  • the proportion of powder-to-liquid feed is such that a pelletizing amount of liquid is supplied, i.e. an amount which results in the formation of pasty wet pellets rather than dusting out as occurs from use of insuicient liquid or mudding out which results from using an excess of liquid.
  • the necessary proportions are usually well known to those skilled in the art of pelletizing any particular powder with a given liquid, but can be easily determined in any case by means of a few simple experiments.
  • the powder and pelletizing liquid can be combined prior to introduction into the pelletizer, but mixing of the two can usually be accomplished very quickly and eiciently in the pelletizer, thus oblivating a need for premixing.
  • the wetted powder mass is vigorously agitated by rapid rotation of the shafts 3a and 3b, which causes the pins 6a and 6b to move through the mass.
  • Rotary motion of the shafts gradually advances the wetted powder axially through the pelletizing zone toward the outlet 11, and also rapidly swirls the powder so that it is slung out against and is moved around the curved wall of the conduit 2.
  • the wetted powder leaves the wall and flies into the central portion of the pelletizing zone between the shafts, and is therein intensely ailed by the interdigitating pins 6a and 6b.
  • one portion, the swirling portion against the wall lies in section 1a of the pelletizing zone against the curved wall of the conduit 2.
  • the other portion lies toward the center line of the pelletization zone, section 1b.
  • the curved, longitudinally extending peripheral wall of the conduit 2 closely conforms to the circular path of rotation of the tip-ends of pins 6a and 6b which are not interdigitated. Any of members 6a and 6b which are out of interdigitating relationship during rotation of the shafts are thus moving through that portion of the mass against the wall of conduit 2. As this portion leaves the wall and moves into the central section 1b of the pelletizing zone, it is subjected to the action of pins moving into and out of interdigitation and thereafter moves back to the wall. Accordingly, the mass of wetted powder being agitated and pelletized is repeatedly circulated from the wall of the pelletizing conduit to the interdigitating members and then back to the wall as the mass also advances axially toward the outlet of the pelletizing zone.
  • shaft rotation can be the same or opposite, and the shaft speeds can be the same or dilerent to the extent desired.
  • the shafts can be operated using one motor and a gear system which establishes the sought direction of shaft rotation and speed. More convenient, however, is the arrangement described with reference to FIGS. 1-4 wherein independent, variable speed drive units are employed for each shaft. To additional advantage, one or both of these drive units can be reversible for changing the direction of shaft rotation.
  • the minimum speed at which the shafts should be turned is widely Variable depending upon what particular results desired with respect to mean pellet size, pellet size distribution, production rate, and the like. Generally, speeds which provide a pin tip velocity of at least about feet per second can be employed to advantage, and preferred speeds are generally within the range of about to about 50 feet per second.
  • the pelletizer described herein has been utilized to great advantage in producing pellets of a powder at a greatly increased rate, which are denser after drying, and at a somewhat reduced requirement of a liquid pelletizing medium. It is felt that these benefits are provided by the ability to transfer substantially larger amounts of pelletizing work into the wetted powder mass during the pelletizing process.
  • EXAMPLE 1 A carbon black having the following properties was pelletized in a pelletizer as shown in U.S. 3,535,412 having a single agitating shaft with radially extending pins.
  • the pins had a length of 71/2 inches.
  • the inside diameter of the cylindrical pelletizing conduit was 8 inches and its length was 36 inches.
  • Carbon black properties lrface area (electron microscope), m.2/gm. 110 Dibutylphthalate absorption, cc./ 100 gms. 200 Iodine absorption number 290 Transmission, percent 100
  • the carbon black was fed to the pelletizer at the rate of 90 pounds per hour while water was being introduced at the rate of 165 pounds per hour. Shaft speed of the pelletizer was 950 r.p.m.
  • the resulting wet pellets were then dried to a moisture level of 1.2 percent to provide dry pellets of the carbon black.
  • this same carbon black was pelletized in accordance with the present invention.
  • the pelletizer was equipped with two shafts having agitating members 7%/2 inches long. Each shaft extended through a partial cylinder having an inside diameter of eight inches and a length of 32 inches. Carbon black was fed to this twin shaft pelletizer at the rate of 90 pounds per hour while water was introduced at the rate of 135 pounds per hour. Both shafts were turned at 900' rpm. and were rotated in the same direction. The resulting pellets were then dried as before. Properties of the dried pellets produced in the two experiments was as follows:
  • a method for wet pelletizing carbon black powder with a pelletizing liquid wherein the transfer of work into the resulting wetted powder mass is increased and the amount of pelletizing liquid is reduced below that required by conventional pelletizing yet wherein the weight proportion of pelletizing liquid to the carbon black is suliicient for the formation of wet pellets comprising:
  • pelletizing liquid is selected from the group consisting of water and an aqueous solution of a pellet binder.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
US00156629A 1971-06-25 1971-06-25 Pelletizing process Expired - Lifetime US3751543A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US15662971A 1971-06-25 1971-06-25

Publications (1)

Publication Number Publication Date
US3751543A true US3751543A (en) 1973-08-07

Family

ID=22560369

Family Applications (1)

Application Number Title Priority Date Filing Date
US00156629A Expired - Lifetime US3751543A (en) 1971-06-25 1971-06-25 Pelletizing process

Country Status (7)

Country Link
US (1) US3751543A (it)
BR (1) BR7203507D0 (it)
CA (1) CA970933A (it)
ES (1) ES403727A1 (it)
FR (1) FR2143462B1 (it)
IT (1) IT958947B (it)
NL (1) NL7208165A (it)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4502858A (en) * 1983-03-30 1985-03-05 Phillips Petroleum Company Mixing apparatus
US4867930A (en) * 1981-10-14 1989-09-19 Alfrey Norval K Priller method

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4867930A (en) * 1981-10-14 1989-09-19 Alfrey Norval K Priller method
US4502858A (en) * 1983-03-30 1985-03-05 Phillips Petroleum Company Mixing apparatus

Also Published As

Publication number Publication date
BR7203507D0 (pt) 1973-06-14
FR2143462A1 (it) 1973-02-02
DE2231090B2 (de) 1977-02-10
CA970933A (en) 1975-07-15
NL7208165A (it) 1972-12-28
DE2231090A1 (de) 1973-01-11
ES403727A1 (es) 1975-05-16
FR2143462B1 (it) 1977-12-23
IT958947B (it) 1973-10-30

Similar Documents

Publication Publication Date Title
US2213056A (en) Apparatus for treating dry flocculent powders
US2436771A (en) Method of making pellets
US3163403A (en) Mixing machine
US3730663A (en) Pelletizer
RU2339666C2 (ru) Гранулированная сажа
US6231624B1 (en) Process for continuous dry granulation of powered carbon black
US3900547A (en) Apparatus and method for forming pellets
US3836336A (en) Apparatus for continuous xanthation and solution of alkali cellulose
US2803038A (en) Pelletizing apparatus
US3852399A (en) Process for the production of carbon black beads
US3333038A (en) Method for wet pelletizing carbon black
US3751543A (en) Pelletizing process
US3353208A (en) Apparatus for forming pellets
US2477009A (en) Manufacture of plastic molding powders
US4074864A (en) Method for producing polycarbonate powder from a polycarbonate solution
US3956445A (en) Pelleting of carbon black
US3535412A (en) Process for producing improved pellets of a powder
US4136975A (en) Carbon black pelleter
US3579717A (en) Apparatus for pelletizing carbon black
US3607086A (en) Apparatus for wet-pelletizing carbon black
US2232145A (en) Method of granulating superphosphate
US4512732A (en) Heat treating of material in finely divided form
US3593372A (en) Wet-pelletizing apparatus
US4083669A (en) Carbon black pelleter with internal fluid injection
US2100599A (en) Mixing and grinding mill