US2460938A - Method and apparatus for cleaning asbestos - Google Patents

Description

F eb. 8, 1949.

Filed Aug. 5, 1944 METHOD AND-APPARATUS FOR CLEANING ASBESTOS 2 Sheets-Sheet 1 BY/U- of" ATTORNEY Feb. 8, 1949. F, J, KOEHNE 2,460,938

METHOD AND APPARATUS FOR CLEANING ASBESTOS Filed Aug. 5, 1944 y Tula.

www@ Ich ATTORNEY and is particularly Patented Feb. 8, 1949l METHOD AND APPARATUS FOR CLEANING ASBESTOS Frank J. Koehne, Martinsville, N. J., assignor to Johns-Manville Corporation, New York, N.v Y., a corporation of New York Application August 5, 1944, Serial No. 548,295

16 Claims. l

This invention relates to the opening and cleaning of asbestos and similar iibrous materials, concerned with improvements in method and apparatus whereby asbestos may be simultaneously opened and cleaned to segregate the fibers and fine and coarse impurities including dust and rock particles adhering thereto Crude and partially opened asbestos fibers such y as are presently available for industrial purposes consist of rodlike bundles of. desirable iine asbestos bers or laments with which are associated substantial amounts of undesirable impurities including asbestos iines, rock gangue and dust. Conventional methods of treating such unclean asbestos fibers, as by milling, windowing and screening to separate impurities therefrom, vdevelop serious attrition and breakage of the fibers, thus producing a librous product which has a market value substantially lower than the potential market value oi the unbroken i'lbers.'

Dilculties are to be expected in attempts to apply conventional pneumatic impact pulverizing and cyclone separating and classifying methods and equipment designed for handlingl granular products, to the problem of cleaning crude and unclean asbestos. signed for cyclone classification of granular products are predi-cated on Stokes Law, which applies specifically to granular particles but not to. brous materials such as asbestos. The separation of granular particles according to Stokes Law is effected according to particle size, or more accurately in accordance with-the average diameters and masses of the particles. tempt to adapt cyclone separating and ing equipment designed for handling materials, to the treatment of brous classifygranular material such as asbestos, would necessitate maintenance of suitable turbulence in the pneumatic system in order to cause the fibers to behave as spherical particles such as the equipment is designed to handle. In the absence oi turbulence, the fibers tend to orient themselves into alignment with the longitudinal axis of the cyclone separator and to discharge rapidly under gravity pull from the classication zone. When librous materials are subjected to suilicient turbulence to cause Methods and equipment de- Any atthem to behave as spherical masses in a pneumatic vortex cleaning system, any cleaning effect which may result from such treatment is at least partially cancelled by the tendency of the opened fibers to attract back to their enormously greater exposed arca surfaces impurity nes and dust initially liberated during impact pulverizing 2 treatment. Accordingly, the more thoroughly the brous bundles are berized or opened by the initial impact pulverizing treatment, and the greater the resultant ratio of length to thickness of the iibers, the less easily can the opened bers be cleansed of iine non-librous impurity particles or dust by conventional cyclone cleaning and classifying equipment.

A primary object of the invention is to provide method and apparatus of improved characteristics adapted to eiliciently and economically open and clean crude and unclean asbestos bersl.

A more particular object is that of providing improved method and apparatus whereby crude and unclean asbestos bers may be simultaneously opened and separated from coarse and iine impurities including rock particles and dust adhering thereto, while avoiding serious degradation of the fibers.

According to the present invention, asbestos bers undergoing treatment must be thinly suspended in an air stream of suflicient volume to accept and carry away impurity dust particles as they are'separated from the ber filaments. The crude or unclean asbestos bers are introduced into the upper portion of an upright generally cylindrical opening and cleaning chamber, and the fibers drop gradually by gravity pull through an upwardly rising vortex of cleaning gas or air. Means such as rotating paddle or fan blade assemblies are provided for establishtions of the vortex. Centrifugal force actinguniformly on the libers, tends to' suspend them and hold them adjacent the periphery ofthe vortex and adjacent the walls of the cleaning zone. By maintaining a high ratio of rotational movement in relation to gravitational downward movement, the bers are caused to travel in a. path of such length as. to comb them into longitudinal alignment with the rotational direction of their movement. Means such as reentrant fins are provided at intervals along the inside walls of the cleaning zone, which act to intermittently or periodically deilect the rotating body of suspended fibers and suspending Igas or air inwardly away from the walls of the cleaning zone. The bers resist the intermittent deilection impulses thereby created by virtue of their greater momentum. The bers are thereby ilexed and bent by the more compressible and deflection responsive air impulses, as successive portions of each liber lament length are subjected to these pulsating lateral impulses. The resulting exing and bending opens the fibers and chips off attached impurity particles, Movement of the suspending air or gas transversely back and forth across the fiber filaments scours the filaments of adhering dust and rock particles. while avoiding serious attrition of the fibers or recontamination thereof by the separated dust. This opening and cleaning operation is followed by final classification segregation of clean fibers from liberated granular and dust particles by'selective action of centrifugal, gravitational and rising gas vortex suspension forces.

With the aforementioned objects and features in view, the invention consists in the improvements in method and apparatus for cleaning and berizing asbestos and similar fibrous materials which areherelnafter described and more particularly defined by the accompanying claims.

In the following more complete description of the invention, reference will be made to the attached drawings, in which:

Fig. l is a diagrammatic assembly'view, with parts shown in vertical section. of a preferred' arrangement of apparatus adapted for the practice of the invention;

Fig. 2 is a horizontal section of one of the fiber cleaning chambers, taken on the line 2-2 of Fig. l;

Fig, 3 is a horizontal section through a segment of an inverted truste-conical lining of one of the cleaning chambers. taken on the line 3--3 of Fis. 1;

Fig. 4 is a horizontal section through a segment of the inverted frusta-conical lining in the upper portion of the last cleaning chamber of a series, taken on the line l-A of Fig. l; and

Fig. 5 is a horizontal section through a segment of the inverted frusta-conical lining in the lower section of the last cleaning unit of the assembly shown in Fig. l, taken on the line S-S of Fig'. .1.

The improvements in method and apparatus of the present invention are designed to effect the berizing and cleaning of fibers while thinly sus` pended in air, and to develop enicient separation f and segregation of cleaned fibers and fine and coarse non-fibrous contaminants in the same operation in which the fibers are flberized and liberated from such contaminants.

A preferred apparatus assembly for the practice of the invention is portrayed in Fig. l. This 'apparatus may include a shaker screen I0 from is effected through a tangential offtake 34 from which this air is carried to a cyclone fiber separator 36. Central air exit ports of each of the cyclone air separators 32 and 3G may be connected to the inlet of a common suction fan 38. The discharge nozzle of fan 38 is shown as connected to the tangential inlet of a cyclone dust separator 40.

Inverted frusta-conical inner lining members 42 have been shown as mounted in the lower portion of each cleaning chamber I6, I8 and 20. The upper top rim of each lining member 42 is dimensioned for mounting to form a tight sealing fit with the inner cylindrical wall of the chamber. A similar inverted frusto-conical inner lining Mi is shown as mounted adjacent the top of clean- A ing chamber 20. Reentrant fins 46 and adjacent cated tangentially near its base.

slots I8 are shown las located at spaced intervals around the lining members 42 and M in relative arrangements and for purposes which are hereinafter more fully explained. Each of chambers I6 and I8 has a cleaned fiber exit port 50 lo- Chambers I5 and I8 also have coarse impurity exit ports which coincide with the axial air intake ports 2E.

Chamber 20 has a gas pervious frusto-conical base 52 and an impurity granule exit port 54 at the base circumference.

In operation, an air or gas suspension of unclean asbestos fibers is picked up by suction from shaker screen feeder Iii (Fig. l). Vibrating or shaker screen feed tables of the type shown are advantageously employed for initially cleaning mixtures of short asbestos fibers and rock gangue. Fiber containing excessive rock content may be advantageously fed over a shaker or vibrating screen having an air inlet I I directed through its screen bottom through which air may be forced upwardly for the purpose of elevating and maintaining the bers in a blanket above the rock on the screen to give the suctiony hood i2 every opportunity to remove such fibers as were formerly weighted down by rock during the brief interval of their passage under the suction hood. Longer grades of asbestos fibers may be supplied to the cleaning chambers of the present equipment by a picker-belt feed mechanism.

Crude or unclean fiber is delivered through inlet ports I5 into the top portion of each of the cylindrical cleaning chambers I6, I8 and 20. The

` paddle or fan assemblies 2-4 operate to suck a the top of which fibers to be cleaned are picked up by a suction hood I 2 and transported in air suspension through a suction fan I'l. From fan i4 the air suspended fibers are discharged into the upper peripheral section of the first of a series of upright cylindrical ber opening and cleaning chambers or drums IB, I8 and 2U. Motor driven vertical shafts 22 are mounted axially in each of the cleaning chambers I8, I8 and 2li, each shaft being supported by top and bottom bearings. Two vertically spaced sets of fan blades or paddles 24 are shown as rotatably mounted on each shaft 22 in position to develop suction intake of cleaning air or gas through an intake port 2 at the base of each chamber, ansi to promote rotation of the air within each cleaning chamber in an upwardly rising air vortex. Air thus introduced into cleaning chambers I6 and I8 finally escapes therefrom through axial top oitakes 28, from which it is conducted by pipes 30 to cyclone dust separators 32. Escape of air which is introduced into cleaning unit 20 large volume of cleaning air into each chamber through the bottom air intakes, and to generate in each of the chambers an upwardly7 rising air vortex which picks up the unclean fibers and retards the rate at which they settle through the chamber under gravity pull, while transporting the fibers in suspension and under the inuence of centrifugal force in a long path around the inner periphery of eachcleaning chamber. By thus forcing the bers to travel in a circular path around the inner lining of the cleaning chamber, their path of travel is so extended as to afford ample time for the orientation of the fibers with their major axes aligned with the direction of rotational travel. This centrifugal force tends to pin the bers to the outside walls of the cleaning chambers.

Fins 45 which are attached at spaced intervals to the inside surfaces of the chamber lining, serve to periodically deflect the rapidly circulating air and ber stream toward the laxia1 center of the cleaning chamber in a. direction opposed to the direction normally imposed by centrifugal torce. Since the. entraining air is compressible, ;centrifugal force. intermittently op posed by the` deflecting action ofthenns 4I. develops a fluctuating pumping action forcing Vthe air transversely in and out across the path of the moving fibers, vwhereas the greater momentum of the fibers tends to keep them travelling in a circular path and to resist such deflection. The result of such pulsating of the compressible air carrier is to cause bending 'and flexing of the fibers, as successive portions of their lengthenter and leave the areas wherein this lateral pulsation is induced. The flexing and bending of the individual fibers or fiber bundles tends toopen and split the fibersand to chip loose from their surfaces any adhering dust and granular impurities. o celeration between the fibers and the entraining air develop a scouring action upon the flexing fibers, which stili further aidsseparation oi' non fibrous impurities from the fibers. The clean air which is brought in from the bottom gradually works its way upward through the cleaning chambers as a vortex from which the air finally exits at ports 28 carrying with it an entrapped load of fine impurity dust liberated from the fibers.

Variations in rate of movement or ac- Fins 48 may be attached directly to the vertical cylindrical walls of the cleaning chambers I6 and I8. However, it is deemed advantageous to erect such fins in the form of an inverted frusto'- conical cone 42 having its upper and larger rim dimensioned to the inner circumferential dimensions of the cleaning chamber and rigidly attached thereto. With this inverted frusto-conical arrangement of the reentrant fins as an inner lining for the cleaning chamber, part of the air which is introduced to the base of the chamber may be circulated around the outside of the fin lining and finally introduced to the cleaning chamber through slots 48 disposed immediately behind the reentrant fins, in the manner particularly shown by Fig. 3. With this modification, an inrush of additional cleaning air takes place through slots. immediately adjacent and behind each reentrant fin in the path ofthe air and fiber which is circulating within the heating chamber. As the iibersand suspending air travel across and adjacent each fin, a pressure drop takes place in the eddy current immediately behind the fin, and this pressure drop develops inrush of additional cleaning air through a slot 48. After the air and suspended fiber has passed the fin 46 and the slot 48, unopposed centrifugall force operates to again drift the air suspended fiber toward the circumference. of the chamber through the additional body of cleaning air thus suppliedby slot 48.

The general movement of cleaning air through the chambers I8 and i8 is upward and then inward. As the fibers gradually descend through this rising vortex oi.' air, the air operates to pick up fine dust and nes liberated by the fibers and to carry ofi' suchfines in suspension through. the air exit. Introductionvof cleaning air through slots 48 tends to displace dust laden air inwardly toward the exit 28 of the cleaning chamber. while the outer layers of air suspended fibers are subjected to bathing and scouring by added cleaning air.

The-cleaning chambers are designed to operate gently on crude, unopened fiber bundles to fiberize such bundles by flexing and by mild impact against the reentrant fins and chamber linings, While cushioning the fibers against serious disintegration. Any crude unopened fiber until their. classification and physical characteristics meet acceptable specifications.

Suitable dimensions for the cylindrical cleaning chambers I6, I8 and 20 include lengths of about 4% ft. and internal diameters approximating 3 ft. The fans which develop and maintain a rising vortex of air throughout the chambers may be four bladed fansof approximately 2 inch blade width located in sets mounted respectively at elevations of approximately six inches and 36 inches above the bases of the cleaning chambers. Buch fans lare rotated at speeds which are adjustable maintain air velocities in the range 30D-1500 ft. per second at the periphery of the upwardly rising air vortex. Peripheral air speeds lower than 300 ft. per-second are unsatisfactory because the Dull of gravityallows the fibers to settle out of the cleaning unit at a rate too fast to permit suitably eiilcient flberizing and cleaning action. Air velocity rates substantially greater than 1500 ft. per second tend to develop excessive ilberizing and breakdown of opened fibers, causing undesirable shortening of open fiber length. The apparatus shown in Fig. 1 is designed tc effect substantially complete separation of fine sage through chambers i8 and I 8. and to utilize chamber 20 for effecting final separation of clean opened fibers from coarse rock and unopened crude fibers. by settling out such coarse impurities. The inverted frusto-conical lining 44 which is mounted in the upper portion of chamber 20 is designed to act as a removal trap or gate for' the clean and opened' fibers. The fiber with its entrainingy air is fed into the top of chamber 20, and as it settles it is moved by centrifugal force by the upwardly rising air vortex toward the periphery walls of the chamber. As the fibers travel in a rotational path adjacent the inner face of cone 44, they pass over defiecting iin elements 48 (Fig. 4), behind which fins lie slots 48 which form the only means of egress for the air and opened fibers leaving the cylinder 20. Fibers which have been sufficiently cleaned and opened l can be made to reverse their direction of travel and to emerge through the slots 48 in cone 44,

while heavier and coarser incompletely opened crude flbersand'coarse granular impurities are carried by their greater momentum past the slots 44 and are thereby retained within the chamber while settling under gravity'pull into the lower portion of chamber 2li. i

The arrangement of defiectingfins 46 and slots 48 in cone 42 at the base of chamber 20 may be such as portrayed in Fig, 5. In this casethe reentrant iins are turned inwardly in a direction opposed -to the direction ofrotation of the air' within the chamber, with the forward or scalping edges 5I of such fins presented as traps for heavy particles carried by the rotating air in closely4 abutting relation to the inner wall of cone 42.' Centrifugal force rotates the entrained rock and through the treating-chamcrudy fibers directly toward the forward'scalping I8, and such particles are trapped and elected outwardly by the scalping edge and n through the slot louvers forwardly of the: iin elements, and

settle by gravity to the base of the chamber il, where they are discharged through the outlets I4.

Any sulciently opened bers which are present J:Medocal prolonged and repeated exing.' bending and scouring treatment of the bers while supporting them in ges suspension, as the principal ber opening'and cleaning inuence. A substantial s ber opening and cleaning effect is developed by the turbulence obtained at points adiacent the rewentrant dns, asa result of impingement and-collision of impurity particles and bers. Important factors in the summation of mechanical disinlo tegration as the chief fiberlzing inuence consist in the air stream flowing past the inner lining of the bottom. cone 42 in chamber 20 are deflected away from the scalping `edges of the ns Il by the blasts of air entering through ports 48. and such kfibers are carried forwardly out of the lower section of the chamber by the rising air vortex and finally exit from the chamber through the exit ports in cone Il.

The principal ber opening and cleaning sections of the illustrated apparatus lie in the zones of chambers i8 and i8 which are confined radially -by the inverted frusto-conicai defiector fin linings. That portion of each of chambers il and Il which underlies the restricted neck at the base of the inverted cone forms a radially extended classlcation zone in which the opened or partially opened bers are thrown outwardly by the rotation of the revolving fan blades 2l, to be removed tangentially from the base of the apparatus. while heavy impurities of more nearly spherical shape are discharged from the bottom of the inverted cone toward the centrally located air inlet port, in a zone where the centrifugal forces are insufficient to throw such granular particles toward the periphery. In other words, the final segregation of the opened and cleaned bers from the heavier or coarser impurities. takes place in the lower portion of the cleaning chambers below the point at which a powerful vortex is developed. In the upper portions of the chambers I6 and I8 the operation which takes place is primarily that of segregation and classification of crude or partially opened asbestos and of light dust or fine impurities. The light dust particle impurities are carried off by entrainment in the inwardly moving air stream which exits from the axial top center of the chambers, whereas the heavier crude and partially unopened bers are forced toward the outer periphery of the vortex by centrifugal action.

The method and apparatus which is herein described is particularly directed to the purpose of effecting opening and cleaning of crude asbestos without serious disintegration or attrition of opened and cleaned fibers. To accomplish this purpose, the individual nberizing and cleaning chambers of the apparatus are preferably limited in size to a, comparatively low unit treating capacity, and several of such units are preferably operated in series, in order that the partial ber opening and cleaning operation which takes place in 'one unit may be carried forwand to completion in a succeeding unit. In traversing one of the flberlzing and cleaning units I6 or I8 from its top liber inlet to its bottom tangential liber outlet, the crude or partially opened fibers are subjected to only mild mechanical impact or impingement contact with the wall and fin surfaces of the cleaning chamber and with the blades 2l of the' impeller fans. Provision is made to reduce as much as possible suchmechanical impact treatment of the fibers, and to substitute therefore a of: limiting the velocity of the carrier gas stream at the periphery of the vortex to a maximum of not to exceed 50 times gravity pull: developing transverse pulsations in the path of the bers by interposing deector ns which extend not more than an inch or two radially inwardly of the vortex periphery and which extend in a direction forming a small oblique angle with the direction of ber movement: and introducing blanketing air streams behind the deiiector fins and in the direction of ber ow to partially .counterbalance the centrifugal forces acting to push the open bers into contact with the walls of the cleaning zone. Such factors cooperate to limit serious attrition of fine open bers, without interfering too seriously with the forces applied to eect opening and cleaning of heavier unopened and crude nbers. t

The present method of treating asbestos bers is a highly e'icient and simple operation in which an upwardly rising gas vortex is utilized for substantially simultaneous ber opening and cleaning operations and for classification and segregation of the resulting cleaned bers from heavy non-brous and light dust impurities, In the inner or axial zones of the vortex the material suspended in the vortex is classied by centrifugal forces, and all bers and impurities greater than-a desired size are returned to the outer periphery of the vortex by a centrifugal force of 10-50 times gravity. By continuing the upward and inward movement of the vortex through a zone which lies above the principal flberizing and cleaning zone, a highly efficient classification is secured in which substantially all impurity particles below a predetermined size are entrained by the air which leaves the cleaning chamber through the central air exit port. The inverted cone frustrum linings which are mounted in the berizing and cleaning sections of each treating chamber operate somewhat as reverse venturis on the upwardly and inwardly spiralllng air vortex, by reducing the velocities of the inward and rotational components of the air flow in the upper zones of the chamber, thus concentrating the ilber opening and cleaning section of the apparatus primarily within that section of the apparatus which is bounded by the cones, while promoting final classification and separation of light dust impurities by entrainment, in the upper zone of the cleaning chamber.

Operations which take place in the last cleaning chamber 20 of a series are primarily those of classiiication and segregation, although this chamber is also designed to carry out some opening and cleaning treatment of crude iibers. In

this chamber the general flow of bers from the bestos ber opening and cleaning method of the present invention, the following results were obtained by treating a measured charge of unclean crude asbestos bers in apparatus of the dimensions heretofore given, assembled in the manner portrayed in Fig. 1. The crude bers as charged to the apparatus contained a usable ber content of 53% by weight, and said crude bers classied as to size with an average length of approxi'- mately 62 microns and an average diameterof approximately 58 microns. The crude bers were delivered to the apparatus at a feed rate of 600 lbs. per hour, and the treatment was carried out supplying air to each cleaning unit at the rate of 400-450 cu. ft./minute. The yield of still incompletely cleaned open bers which was obtained in ber separator 36 was 63% by weight of the crude ber charged to the unit, and such clean bers classied to an average length of approximately 350v microns and an average diameter of approximately 18 microns. The large apparent increase inA average ber length results from removal of a high proportion of very short bers or nes by the classication process. The heavy gangue which was discharged from the base of the last cleaning chamber 20 analyzed 17.4%

ofusab'le crudy ber, and the lightdust which was accumulated in dust separators!! analyzed 28% of very ne short bers of a grade suitable for use in the manufacture of asbestos paper,

asbestos-cement shingles and plastics. By this opening and cleaning method as applied to crude asbestos it is possible to recover a major portion of the brous content within very narrow size classification limits and to separate undesired short bers in a manner which makes them readily available for other uses as llers and the like. Since many variations may be made from the illustrative details given. without departing from the scope ofthe invention, it is intended that the invention should be limited only by the terms of the claims.

What I claim is:

1. The method of treating asbestos bers to separate coarse and ne impurities adhering thereto comprising, introducing the bers to be cleaned into an upwardly spiralling vortexv of a gaseous uid, maintaining a high volume ratio of gas to ber to provide a, thin suspension of bers, maintaining a high ratio of rotational movement in relation to gravitational movement4 of bers whereby to develop a path of ber travel of such length that the bers are combed into longitudinal alignment with the rotational direction of their movement, periodically deecting the rotational gas ow inwardly at spaced points adjacent the periphery of the vortex,thereby developing components of lgas movement which are transverse to the direction of ber rotation and causing exing and bending of the bers whereby to loosen and scour impurities from the ber surfaces, and nally separating the clean bers from heavy granular impurities and from light dust impurities by removing the bers peripherally from the vortex while entraining the dust in the upwardly moving gas and removing heavy impurities by gravitational settling.

2. The method of opening and cleaning crude asbestos. bers which comprises, suspending the bers in an air vortex while rotating the air adjacent the periphery of the vvortex at a velocity suicient to comb the bers into longitudinal alignment with the rotational direction of their movement, periodically developing air movement adjacent the periphery of the vortex in a direction transversely to the direction of ber move 4. The method of treating crude asbestos bers to open'vthe bersl and separate impurities comprising, suspending the crudy bers in an upwardly moving airV vortex while rotating the air adjacent the periphery ofthe vortex at a velocity suicient to comb the bers into longitudinal alignment with the rotational direction of their movement, deecting the ow of airat intervals adjacent the periphery of the vortex to eect periodic air movement transversely to the direction of ber. movement whereby to lilex and bend the bers, thereby splitting the bers and liberating impurities, and adjusting the rotational and vertical components of the air ow to eilect separation of ne impurities by entrainment in the upwardly movingair and separation of heavy impurities by gravitational settling, while removing clean opened 'bers from the periphery of the vortex. c v

5. The method of treating crude asbestos vbers -to open the bers and separate impurities comprising. suspending the crudy .bers in an upwardly moving air vortex, rotating'the air adjacent the periphery of the vortex at a velocity sufllcient to comb the' bers into longitudinal alignment with the rotational direction of their movement, deecting'the ow of air -at intervals adjacent the periphery of the vortex -to effect periodic air movement transversely to the direction of ber movement whereby to ex and bend the bers; thereby splitting the bers and liberating heavy impurities, vertical components moval ofbers by adjusting the rotational and of the air ow to effect resuspension in the upwardly moving vortex, and removing heavy impurities from the periphery of the vortex by centrifugal action while simultaneously introducing clean air laterally to the vortex at the points of heavy imv purity removal at a rate suicient to prevent removal of clean ber by centrifugal action.

6. The method of simultaneously opening and cleaning crude asbestos bers whilegavoiding substantial degradation thereof which comprises, continuously feeding bers to be cleaned at a measured rate into an upwardly spiralling vortex of a gaseous uid, maintaining a high volume ratio of gas toiber to provide a thin suspension l high ratio of rotational ii tational gas ow inwardly et spaced points adja= cent the periphery of the vortex, thereby developing components of gas movement which are transverse to the rotational direction of ber movement and causing flexing and bending of the bers whereby to open the bers and loosen and scour impurities from the ber surfaces, and nally separating opened and cleaned bers from heavy crudy bers and granular impurities by removing the clean bers peripherally and selectively from the vortex.

'7. The method of treating asbestos bers as dened in claim 6, including the step of removing ber in suspension outwardly from the periphery of said gas vortex by causing `a reversal in the directional flow of the ber by' establishing a pressure drop between the path of ber' removal and the periphery of the vortex, and adjusting the pressure differential thus established to avoid contamination of the' removed bers by gas carrying nonbrous impurities in suspension.

8. The method of opening and cleaning asbestos bers which comprises, forming and maintaining an upwardly s piralling vortex of air, introducing asbestos bers to be treated into said air vortex, maintaining a high volume ratio of air to ber to provide a thin suspension of bers, adjusting the. rotational and upward ow coniponents of the air body toL maintain a high ratio of rotational movement in relation to gravitational downward movement of the bers, whereby to develop a path of ber travel of such length that the bers are combed into longitudinal alignment with the rotational direction of their movement, deecting the air ow at intervals adjacent the periphery of the vortex whereby to develop components of air movement which are transverseto the direction of rotation, thereby causing exing and bending of the bers and loosening and scouring of rock and dust impurities from the ber surfaces, and simultaneously opening the bers while avoiding substantial degradation thereof by said exing and bending treatment.

9. The method of treating crude asbestos bers -to open the bers and to separate rock gangue and dust adhering thereto comprising, suspending the crudy bers in an upwardly moving 'air vortex while rotating the air adjacent the periphery of the vortex at a velocity suicient to com-b the bers into longitudinal alignment with the rotational direction of their movement, deiiecting the ow of air at intervals adjacent the periphery of the vortex to effect periodic air movement transversely to the direction of ber movement whereby to ex and bend the bers,

,thereby splitting the bers and liberating rock gangue and dust therefrom, and adjusting the rotational and vertical components of the air flow to effect separation of granular gangue particles by gravity settling and of ne dust particles by suspension in the upwardly moving vortex.

10. The method of opening and cleaning crude asbestos bers which comprises, establishing and maintaining two upwardly spiraling vortexes of air, introducing asbestos bers to be treated into the upper portion of the rst air vortex, discharging partially cleaned bers tangentially from the bottom of the rst vortex into the upper portion of the second vortex, maintaining in each vortex a high volume ratio of air to ber to provide a relation to gravitational downward movement of bers whereby to develop a path of ber travel of escasas such length that the fibers are oriented into gitudinal alignment with the rotational dir. of their movement, deecting the air ow at *ntervals adjacent the periphery ci each vor tex whereby to develop components of air movement which are transverse to the direction of rotation, thereby causing exing and bending oi the bers and opening and scouring of impurities from the ber surfaces while avoiding substantial degradation thereof; separating light dust impurities from the bers in the rst vortex by entrainment removal of said dust in air discharged axially from the top of the vortex, and separating cleaned bers from heavy granular impurities and unopened bers by entrainment of opened and cleaned bers in air discharged tangentially from the upper portion of the second vortex.

ll. Apparatus adapted for the opening and cleaning of asbestos bers comprising, two upright cylindrical chambers, means in each chamber for developing and maintaining therein an vupwardly rising gas vortex, an inlet port in each chamber for introducing ber to be treated into the upper portion of the vortex, an exit port in each chamber for removing cleaned bers tangentially from said chamber, a conduit connecting the exit port of one chamber in series with the ber inlet port of the second chamber so that ber discharged from the tangential outlet of the first chamber is introduced through the ber inlet port` of the next chamber, and a ber opening and cleaning zone in each chamber, said zone being largely conned within an inner wall lining extending throughout a substantial proportion of the chamber length comprising spaced reentrant ns each projecting a short radial distance inwardly into the path of the vortex.

12. Asbestos ber opening and cleaning apparatus comprising an upright cylindrical chamber, an vair inletr port located centrally at the base of the! chamber, a tangential air exit port located in the upper peripheral portion of said chamber, means for establishing and maintaining an upwardly rising air vortex within the chamber, an inverted frusto-conical baiiie projecting inwardly and downwardly from the upper portion of the chamber wall above and in front of the air exit port, spaced peripheral slots in said baille, deflecting ns projecting inwardly in front of each slot in the direction of vortex ow, and means in the lower portion of the chamber designed to segregate and separate heavy and coarse impurities from clean ne bers suspended in the upwardly rising vortex, said means including scalping ns projecting inwardly a short distance at spaced intervals about the periphery of the vortex in a direction opposed to and forming an oblique angle with the direction of vortex ow, and slots positioned immediately in front of each n in the direction of gas ow, the forward edge of each fin forming a means for trapping and deecting through said slots heavy coarse impurities brought in contact therewith under the centrifugal force of said vortex.

13. Asbestos ber cleaning and separating apparatus comprising, an upright cylindrical drum, gas intake and discharge ports located respectively at the base and top of the drum, a ber charging port opening into 'the top of the drum, a tangential ber discharge port at the base of the drum, means for establishing and maintaining an upwardly rising gas vortex within the drum, an inverted frusto-conical inner lining for the lower portion of the drum having its upper rim engaging and attached to the drum walls, said 13 lining being spaced from the drum wall over a major portion of its height, slots at spaced intervals around the periphery of said inner lining, and deflector fins extending inwardly a short distance at an oblique angle in front of each slot in the direction of vortex flow.

14. In cyclone opening and cleaning apparatus for unclean asbestos, the combination of an upright cylindrical drum, means for establishing and maintaining within said drum an upwardly rising air vortex, means for introducing fibers to be cleaned into the upper portion of said vortex, an inverted frusta-conical lining mounted in the drum with its top rim engaging and attached to the drum walls, said lining being spaced from the drum walls over major portions offits height slots at spaced intervals around the periphery of said lining, a tangential air outlet ported out of the drum behind thellining, delecting ns in front of each slot in the lining in the direction of k vortex now, and scalping ns behind each slot in the lining in the direction of vortex flow.

15. Asbestos fiber cleaning and separating apparatus comprising an upright cylindrical drum, gas intake and discharge ports located respectively adjacent the base and top of the drum, a ber charging port opening into lthe top of theV drum, a tangential ber discharge port at the base of the drum, a heavy impurity discharge port located centrally at the base of the drum, an inverted frusta-conical inner lining for the lower portion of the drum,

each slot in the direction of vortex flow, and sets of fan blades mounted labove and below the frusta-conical lining within the drum and arranged to establish and maintain an upwardly rising vortex within the drum.

16. In cyclone opening and cleaning apparatus for crude bers, two upright cylindrical drums, means for establishing and maintainingwithin each drum an upwardly rising air vortex, charging ports for introducing bers to be cleaned into the upper portion of each drum, a tangential v the second drum with the -lll ber discharge port at :the a conduit connecting the base of the first drum, fiber charging port of ber discharge port of the iirst drum, an axial air outlet port at the top of the first drum, inverted frusto-conical lining members mounted in a, lower portion of each drum with their top rims engaging and attached to the drum walls, another inverted frusto-conical lining membermounted in the upper portion of the second drum, said lining members being spaced from the drum and positioned in the path of the of their heights, a tangential air and fiber outlet port for the second drum behind Ythe upper lining member, slots at spaced intervals around the periphery of each lining member, deecting fins projecting inwardly in front of each slot in the direction of vortex ow in the upper lining of the second drum and in the lower lining of the rst drum, and scalping fins projectinginwardly behind each slot in the lower lining of the second drum.

FRANK J. KOEHNE.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 505,977 Fletcher Oct. 3, 1893 1,023,750 Morscher Apr. 16, 1912 1,484,208 Davis Feb. 19, 1924 1,505,742 Stebbins Aug. 19, 1924 1,509,915 Stebbins Sept. 30, 1924 1,595,257 Stebbins Aug. 10, 1926 1,595,258 Stebbins Aug. 10, 1926 1,675,941 Lindsay July 3, 1928 1,978,802 Lissman Oct. 30, l1934 2,026,833 Holland-Letz Jan. 7, 1936 2,032,827 Andrews Mar. 3, 1936 2,039,692 Van Tongeren May 5, 1936 2,125,086 Rourke July 26, 1938 2,128,166 Schmidt Aug. 23, 1938 2,128,194 Sheldon Aug. 23, 1938 2,152,114 Van Tongeren \Mar. 28, 1939 2,214,658 Browning Sept. 10, 1940 2,280,903 Ellison Apr. 28, 1942 upwardly rising vortex over major portions' Certificate of Correction Patent No. 2,460,938. February 8, 1949.

FRANK J. KOEI-IN E It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 1, line 16, for the word windowing read willowing; column 6, line 51,

i for periphery read peripheral;

and that the said Letters Patent should be read With these corrections therein that the same may conform to the record of the case in the Patent Oce.

Signed and sealed this 5th day of July, A. D. 1949.

[SEAL] THOMAS F. MURPHY,

Assistant Uommz'ssz'fmer of Patents.

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