Abstract:
A process and apparatus for removing foreign matter from fibers, such as from cotton or flax with significantly reduced damage are disclosed. This cleaning is achieved without any of the condenser, compression rollers, or feed roller and feed plate which are present on conventional lint cleaners.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method and apparatus for separating foreign matter from fibers. More particularly, the present invention provides a method and apparatus for separating entrained and/or adherent foreign matter, such as plant parts and other contaminants, from fibers such as cotton or flax. 
     2. Description of the Prior Art 
     Cotton possesses its highest fiber quality and best potential for spinning when it is on the stalk. Lint quality of the cotton, after it has been picked and baled, however, depends on many factors, including variety, weather conditions, cultural and harvesting practices, moisture and trash content, and ginning processes. The principal function of a cotton gin is to separate lint (fiber) from seed. But the cotton gin must also be equipped to remove a large percentage of foreign matter from the cotton that would significantly reduce the value of the ginned lint. For purposes of the following discussion, foreign matter is understood to include trash and debris such as leaf particles, motes, grass, and bark, displaced dry or wet lint, wet matter, green bolls, cotton seed, and underdeveloped cotton seed that are associated with the cotton ginning process. 
     A ginner generally has two objectives: (1) to produce lint of satisfactory quality for the growers&#39; market; and (2) to gin the cotton with minimum reduction in fiber spinning quality so that the cotton would meet the demands of its ultimate users-the spinner and the consumer. Accordingly, quality preservation during ginning requires the proper selection and efficient operation of each machine that is included in a ginning system. 
     A thorough description of the cotton ginning process and the various components used is described by Anthony, W. S., et al. (Editors),  Cotton Ginner&#39;s Handbook , Agricultural Handbook No. 503, USDA: Agricultural Research Service, December 1994, the contents of which is incorporated by reference herein. In brief, to begin the ginning process, cotton is transported from a trailer, module, or other storage means into a green-boll trap in the gin where green-bolls, rocks and other heavy foreign matter are removed to prevent damage to the machinery. Then, an automatic feed control provides an even, well-dispersed flow of cotton so that the gin&#39;s cleaning and drying system will operate more efficiently. The cotton is subsequently heated in a dryer and cleaned in a cylinder cleaner and stick machine. After drying and cleaning, the cotton is distributed to each gin stand by a conveyer. 
     The cotton enters the gin stand and the saws in the gin stand grasp the cotton and draw it through widely spaced ribs known as huller ribs. The locks of cotton are drawn through the huller ribs into the lower portion of the seed-roll box. The actual ginning process, i.e., separation of the seed and lint, takes place in the roll box of the gin stand. 
     From the gin stand, the cotton is conveyed into a lint cleaner for further removing foreign matter such as trash, plant parts, leaf particles, motes, grass, and bark that may remain in cotton after cleaning, extracting, and ginning. The most common lint cleaner in the ginning industry is the controlled-batt saw lint cleaner (SLC). In the SLC, lint from the gin stand is formed into a batt on a condenser screen drum. The batt is then fed through one or more sets of compression rollers and between a feed roller and feed plate to deliver a batt of uniform thickness onto a saw cylinder. The saw carries the fiber under grid bars. While the fibers are on the saw cylinder, they are cleaned of foreign matter by a combination of centrifugal force, scrubbing action between saw cylinder and grid bars, and gravity assisted by an air current. After the cotton has passed through the lint cleaner, the cleaned cotton is compressed into bales which must then be covered to protect them from contamination during transportation or storage. 
     Although the controlled-batt saw lint cleaner is the most effective cleaning machine in the gin, it is also the most damaging to the fibers. Significant damage to the fibers may occur as they are transferred from the condenser and rollers onto the saw cylinder, and as the fibers are cleaned while on the saw. The saw cylinder rotates at high speed in a direction which is opposite to the flow of cotton from the roller and feed plate. The abrupt change of speed and direction of the flow of the cotton batt as it is engaged by the saw cylinder creates a combing action, which aligns the fibers and gives them a smoother appearance. However, this also subjects the fibers to a high degree of stress, resulting in fiber breakage. Additional fiber damage as well as fiber loss occurs as the fibers are carried by the saw cylinder across the grid bars. 
     While numerous systems for cleaning cotton fibers have been developed, relatively few systems for the recovery and cleaning of flax fibers have been developed in the United States. Two general types of flax (Linum usitatissimum L.) are grown, flax for fiber and flax for seed. The fiber is extracted from the fiber flax stalks, and is typically used in manufacturing items such as linen apparel. The stalk consists of fiber bundles located between the epidermis or bark surface and an inner wood core (shive), and the processes for the separation of the fibers are difficult and expensive. Moreover, the processes normally used for separation of fiber from fiber flax typically require the stalk to be biologically degraded or retted before mechanical processing. In contrast to fiber flax, the seed flax stalk remaining after the seed has been harvested and recovered is usually considered a waste product. Although the flax in the seed flax stalk can be separated, the conventional processes used for separation of fiber from fiber flax, are not feasible for seed flax stalks. 
     Thus, despite the improvements in ginning technology, the need persists for an improved ginning system which will effectively clean cotton while reducing fiber damage and loss. Moreover, there is also a need for an improved system for recovering flax fiber from straw. 
     SUMMARY OF THE INVENTION 
     I have now invented an improved apparatus and method for separating foreign matter from fibers with significantly reduced fiber damage. The apparatus includes: 
     a) a first housing having an inlet for delivering the fiber containing material therein, and an outlet for discharging partially treated fiber therein; 
     b) a separation surface positioned within the first housing, which surface includes apertures therethrough which are effective for allowing passage of the foreign matter; 
     c) a plurality of rotatable first separator cylinders positioned in succession within the first housing above the separation surface, which cylinders include a plurality of projections extending therefrom which are effective for temporarily engaging, moving, and centrifugally releasing therefrom the fibers in the material; the cylinders rotate in the same angular direction such that as the material is engaged by the projections it is transported by successive cylinders through the housing, across the separation surface, and through the outlet; 
     d) a second housing having an inlet in communication with the outlet of the first housing for receiving partially treated fiber therefrom; 
     e) a rotatable second separator cylinder disposed in the second housing, which cylinder includes a plurality of projections extending therefrom which are effective for securely engaging and transporting fibers in the material on the cylinder; 
     f) one or more cleaning bars disposed in the second housing adjacent to the second separator cylinder, such that fibers pass between the cylinder and cleaning bar, while foreign matter in the material is impacted by the bars and removed; and 
     g) a doffing means for removing said fiber from the projections on the second separator cylinder, which first doffing means may include air blast, vacuum, and a first doffing brush cylinder, wherein the first doffing brush cylinder has an outer peripheral surface operably associated with and rotating in the opposite angular direction as the second separator cylinder, which is effective for mechanically removing the fiber from the projections on the second separator cylinder. 
     Fiber containing material for treatment is introduced into the first housing in contact with the rotating first separator cylinders. As the fibers are engaged by the projections on the cylinders, the material is both agitated and transported or pulled across the separation surface below the cylinders. The movement of the material across and against this surface effectively scrubs the material, dislodging foreign matter within the material which matter then falls by gravity through the apertures in the surface. In contrast, the fibers engaged by the projections are released therefrom by the centrifugal force generated by the rotating cylinders, thereby conveying the material to successive downstream cylinders in the housing and repeatedly subjecting the material to the cleaning action. Once the fiber containing material is engaged by the last separator cylinder, this partially cleaned material is propelled off of the revolving cylinder toward and through the outlet of the first housing, and directly into the second housing. In a preferred embodiment, propulsion of the partially treated material through the outlet and into the second housing is assisted by providing one or more optional, outwardly extending wipers or paddles on the last separator cylinder. 
     Fibers in the partially cleaned material delivered into the second housing are seized by and retained on the projections of the second separator cylinder. As the cylinder rotates, the material is transported past the cleaning bars. The fibers retained on the rotating cylinder are subjected to further cleaning to remove any remaining foreign matter by a combination of centrifugal force, the scrubbing action between the cylinder and cleaning bars, and gravity. After the fibers on the cylinder have passed the cleaning bars, the cleaned fibers are removed from the cylinder by the doffing means, whereupon they may be recovered and supplied to a baling machine and/or further treated. 
     In accordance with this invention, it is an object to provide an improved process and apparatus for removing foreign matter from fibers. 
     Another object of the invention is to provide an improved cleaner effective for treatment of fiber from cotton or flax. 
     A further object of the invention is to provide an improved cleaner for effectively cleaning fiber with significantly reduced damage and fiber loss. 
     Yet another object of the invention is to provide an improved saw-type lint cleaner without any of the condenser, compression rollers, or feed roller and feed plate which are present on conventional lint cleaners. 
     Still another advantage of the invention is to provide a single cleaner that achieves all the cleaning of flax necessary to produce a usable fiber from chopped straw. 
     Other objects and advantages of the invention will become readily apparent from the ensuing description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side cross-sectional view of a system for separating fibers from a mixture in accordance with the present invention. 
     FIG. 2 is a partial enlarged perspective view of a concave grid-bar structure for the system illustrated in FIG. 
     FIG. 3 is a vertical sectional view taken in the direction of the arrows and along the plane of line  4  in FIG.  2 . 
     FIG. 4 is an enlarged end elevational view of a pair of rotating cylinders having rods protruding therefrom of the system of FIG.  1 . 
     FIG. 5 is an enlarged end view of a second separator cylinder with associated cleaning bars and optional shroud. 
     FIG. 6 is a side cross-sectional view of a system for separating fibers from a mixture in accordance with another embodiment of the present invention. 
     FIG. 7 is a side cross-sectional view of a system for separating fibers from a mixture in accordance with yet another embodiment of the present invention. 
     FIG. 8 is a side cross-sectional view of a system for separating fibers from a mixture which includes the components of the embodiments of FIGS. 6 and 7 in a first arrangement. 
     FIG. 9 is a side cross-sectional view of another system for separating fibers from a mixture which includes the components of the embodiments of FIGS. 6 and 7 in a second arrangement. 
     FIG. 10 is a side cross-sectional view of a system for separating fibers from a mixture in accordance with the present invention wherein the first and second housings are separate. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The apparatus and method of this invention are effective for cleaning foreign materials from a variety of textile fibers, including but not limited to cotton, flax, polyester and nylon. In the preferred embodiments, the apparatus and method are used for cleaning seed flax straw or stalk, particularly seed flax straw chopped in a forage harvester, and most preferably flax straw free of seeds and approximately two inches in length, or cotton fiber recovered from gin stands in the ginning operation, as an alternative to cleaning with conventional controlled-batt saw lint cleaners, or recovering fibers from pulverized or comminuted tires. In these preferred embodiments, the cotton mixture typically comprises from about 1 percent by weight to about 10 percent by weight of foreign matter, whereas the flax mixture often contains about 70 percent by weight of foreign matter. 
     Referring in detail now to the drawings wherein similar parts of the invention are identified by like reference numerals, there is seen an apparatus  10  for receiving a mixture  11  including foreign matter  12  and fibers  13  (FIG.  1 ). Apparatus  10  is used for separating the foreign matter from the fibers, and thus, foreign matter  12  corresponds generally to plant parts and other contaminants while the fibers  13  generally correspond to cotton, flax, polyester or the like. 
     The apparatus  10  includes a housing  20  which preferably includes a primary separation zone or a first separator in first housing  23  and a second separation zone in second housing  24 . An inlet chute  27  connects to housing  20  and communicates with first separator  23  to provide a path for introducing mixture  11  into first housing  23 . Preferably, inlet chute  27  is a chute for feeding a mixture into the primary separation zone. First housing  23  further includes an outlet  28  for discharging partially treated fiber therefrom. 
     The first separator includes a series of first separator cylinders  30  that extend through, and that are rotatably supported by, first housing  23  while being rotatably driven by one or more motors (not shown), preferably variable speed motors. Each cylinder  30  has a plurality of projections  31  protruding outwardly therefrom for contacting and temporarily engaging mixture  11  to separate fibers  13  from foreign matter  12  and to produce an intermediate mixture of residual fibers and foreign matter  12 . The projections are also adapted to centrifugally release the fibers therefrom as the cylinder rotates without assistance from a doffing brush. As used herein, “centrifugally releasable fiber-engaging projections” refers to projections which are capable of engaging any fibers, either pure or in a mixture with non-fibrous contaminants, and releasing, propelling, or impelling the same because of or due to centrifugal force caused by the revolving or rotating cylinder assemblies. The centrifugally releasable projections in the first separation zone preferably comprise a plurality of generally identical projections, which may radiate from the cylinder or may be positioned at an angle to the radii of the cylinder. Without being limited thereto, projections which are suitable for use herein include spikes, course approximately triangular shaped teeth, rods, angles, straight or curved tines, flanges, rods or the like. The size of the projections is not critical. The length of the projections, their spacing on the cylinders, and the speed of rotation of the cylinders may vary with the type of fiber and desired throughput, and may be determined by the skilled practitioner. In the preferred embodiment, projections  31  preferably have a length ranging from about one inch to about three inches and preferably possess a diameter ranging from about ¼ inch to about ¾ inch. Preferably, cylinders  30  are approximately 12 to 18 inches in diameter and revolve at from about 300 r.p.m. to about 1200 r.p.m. For treatment of cotton fibers, preferred speeds may range between about 900 to about 1200 r.p.m., while flax is preferably treated at speeds between about 500 to about 600 r.p.m. The number of cylinders  30 , may vary similarly. However, in the preferred embodiments, without being limited thereto, the number of cylinders  30  will be between 6 and 15. 
     The last or furthermost downstream cylinder  30  also preferably includes optional outwardly extending wipers or paddles  32 . Additional wipers (shown in FIG. 4) may also be provided on the upstream cylinders  30 . The shape of wipers  32  is also not critical. The wipers  32  may have a variety of shapes, including but not limited to elongated planar or curved surfaces or angles extending partially or approximately completely across the length of the cylinder, and may also radiate from the cylinder or be positioned at an angle to the radii of the cylinder, and they may be constructed from rigid, semi-rigid, or resilient materials. The length, height and number of wipers on the cylinders, may also vary, but should be sufficient to engage and propel the mixture  11 . 
     First housing  23  further includes separating surfaces  34  disposed below the first separator cylinders  30  and in close proximity to projections  31  of those cylinders. The shape of the surfaces  34  and the spacing between the surfaces and cylinders are selected such that the rotation of the cylinder is effective to scrub the mixture  11  against the surface to dislodge the foreign matter  12  which may then fall through the apertures or openings therein. In the preferred embodiment, without being limited thereto, the ends of projections  31  rotatingly pass above the separating surfaces at a distance ranging from about ⅛ inch to about one inch, while wipers  32  preferably pass the separating surfaces at a range from about {fraction (1/32)} inch to about {fraction (1/16)} inch. Separating surfaces  34  may be any suitable surface that is capable of cooperating with projections  31  to assist in separating foreign matter  12  from fibers  13  to produce foreign matter/residual fiber mixture. Preferably, separating surfaces  34  are provided with apertures or openings therethrough which are effective for allowing foreign matter  12  and intermediate mixture pass after being separated from mixture  11 . 
     A variety of surfaces are suitable for use herein, and include but are not limited to parallel, spaced rods or bars, screens, grids, mesh or woven wire, and continuous sheets of material such as metal or polymers having perforations therethrough. In a preferred embodiment shown in FIGS. 2-4, separating surfaces  34  are concave with a discontinuous separation surface  40  having a pair of generally parallel arcuate brackets  41  interconnected by a plurality of parallel spaced rods  42 . The spaced rods  42  are preferably separated by an opening or space  43  that has a dimension preferably ranging from about ⅛ inch to about ¾ inch, while the rods generally have a diameter ranging from about ¼ inch to about ¾ inch. In operation, the projections  31  of revolving spiked cylinders  30  contact the mixture  11  and engage fibers  13  that have entrained and/or adherent foreign matter  12 . While projections  31  are engaged with mixture  11  and are being rotated, they rub and/or scrub the projection-engaged mixture  11  against spaced rods  42  of concave grid rod structures  40 , thereby causing fibers  13  and entrained and adherent foreign matter  12  to separate from rod-engaged mixture  11 . Separated foreign matter  12  falls through spaces  43  between the contiguously spaced rods  42 . A collection chamber and/or transport conduit may be provided below separating surfaces  34  for gathering and transporting the foreign matter  12  for subsequent disposal. 
     After mixture  11  has been scrubbed through the process of being brought into contact against spaced rods  42 , revolving projections  31  throw or propel scrubbed mixture  11  onto revolving projections  31  of the next adjacent revolving cylinder  30 . The centrifugal force from one rotating cylinder  30  causes mixture  11  to slide off the projections and be engaged by the rotating projections of the adjacent rotating cylinder  30 , as best shown in FIG.  4 . The process of scrubbing and subsequently propelling mixture  11  is continued until the last of the series of revolving cylinders  30  is reached, whereupon the remaining mixture, which at this point is fibers and residual foreign matter, is passed directly to the second separation cylinder  50  in second housing  24 . Delivery of the remaining mixture from the primary separation zone in the first housing  23  into the second separation zone in second housing  24  is facilitated by wipers  32  on the furthermost downstream cylinder  30 . Wipers  32  help scrub the mixture  11  along separating surfaces  34 , and propel fibers and any mixture which do not fall through spaces  43  onto the second separation cylinder  50 . 
     Although the device may be operated using a single first separator, the skilled practitioner will recognize that a plurality of first separator units may be disposed in series for greater cleaning, or in parallel for increased throughput, or additional units may be provided for recycling recovered material. 
     A description of cylinder cleaners which may be suitably adapted for use herein as a first separator in this invention are described by Anthony, W. S., et al. (Editors,  Cotton Ginner&#39;s Handbook , ibid, pp. 70-75, the contents of which are incorporated by reference herein). 
     The second separator in second housing  24  contains a second separator cylinder  50  that is rotatably supported in the housing  20  and rotatably driven by one or more motors, preferably variable speed motors (not shown). Cylinder  50  has a plurality of outwardly extending projections  51  (FIG. 5) for contacting and engaging the partially cleaned fiber to separate fibers from the residual foreign matter  12 . In contrast to the projections  31  on the first separator cylinders  30 , projections  51  are adapted to seize and retain the fibers as the cylinder  50  rotates at high speed. The fibers are retained on projections  51  and are not released solely by action of centrifugal force alone but require mechanical assistance such as from doffing brushes. Without being limited thereto, projections  51  which are suitable for use herein include toothed wire, saw teeth or hooks. Cylinder  50  and projections  51  are preferably conventional fiber cleaning saw cylinders, having diameters between approximately 12 to 24 inches, and which are operated at from about 600 r.p.m. to about 1400 r.p.m., and more preferably, from about 900 r.p.m. to about 1200 r.p.m. In a preferred embodiment, one or more optional baffles, shrouds, or brushes  58  may be provided near the outer periphery of the second separator cylinder  50 , positioned effective to direct the fiber propelled from the first housing  23  onto the surface of cylinder  50 . 
     Second housing  24  further includes one or more cleaning bars  54  that extend adjacent to, and in parallel with, cylinder  50 . The cleaning bars typically extend substantially across the length of the cylinder  50 , and are spaced sufficiently near to the projections  51  of the cylinder that foreign matter  12  impacts against the bars. Without being limited thereto, in the preferred embodiment, the cleaning bars are grid bars as used on conventional saw-type lint cleaners, such as described by Anthony, W. S., et al. (Editors,  Cotton Ginner&#39;s Handbook , ibid, pp. 103-113, the contents of which are incorporated by reference herein). The selection of the number of grid bars and their spacing from the cylinder  50  may be readily determined by the skilled practitioner. 
     In accordance with another preferred embodiment, second separator cylinder  50  and cleaning bars  54  are constructed and provided with a fixed or adjustable shroud or louver  56  (see FIG. 5) as described in Anthony (U.S. Pat. No. 5,909,786, the contents of which are incorporated by reference herein). Shrouds may be readily installed and selectively activated to eliminate one or more cleaning bars  54  from cleaning action if the fiber is sufficiently clean. 
     Foreign matter  12  removed by the cleaning bars may be discarded or subjected to further processing as described below. The fiber remaining on the cylinder  50  after passing the cleaning bars contains substantially less foreign matter. To recover the fiber from the cylinder, second housing  24  preferably further includes a first doffing brush cylinder  55  having an outer peripheral surface operably associated with and rotating in the opposite angular direction as the second separator cylinder  50 , and which is effective for mechanically removing the fiber from the projections on the second separator cylinder  50 . Although any conventional doffing brush may be used, including those with brush sticks, use of a solid face brush such as a spiral wound doffing brush is preferred to significantly reduce noise levels (see Anthony, W. S., et al., Editors,  Cotton Ginner&#39;s Handbook , ibid, pp. 98-99, 104-105, and 284-285, the contents of which are incorporated by reference herein). The tip speed of the first doffing brush cylinder must be greater than the tip speed of the projections  51  on the second separation cylinder  50  for effective removal of the fiber therefrom, with brush tip speeds preferably being approximately 1.5 to 2 times the tip speed of the second separator cylinder. In the alternative to doffing brush cylinders, it is envisioned that the fibers may be removed from the second separation cylinder pneumatically by suction or air blast as is known in the art. Fiber removed from the second separator cylinder  50  may then be collected for baling or further treated or cleaned. 
     In one alternative embodiment shown in FIG. 6, a third separator cylinder  60  (with cooperating second cleaning bars  64 ), and a second doffing brush cylinder  65  are provided downstream of the first doffing brush cylinder  55 . The construction of the third separator cylinder  60 , cleaning bars  64 , and second doffing brush cylinder  65  may be substantially the same as described hereinabove for the second separator cylinder  50 , cleaning bars  54 , and the first doffing brush cylinder  55 , respectively. Optional fixed or adjustable shrouds or louvers may also be provided in combination with this third separation cylinder  60  and cleaning bars  64  as described for use with the second separator cylinder  50  hereinabove. Moreover, in a modification of this embodiment, the fiber may be removed or doffed from the second separator cylinder  50  with a cylinder other than a doffing brush. It is understood that a doffing cylinder, which may be a saw or other separator cylinder such as described for the second separator cylinder above, may be substituted for first doffing brush cylinder  55 , provided that this doffing cylinder is also rotating at a faster speed than second separator cylinder  50 , but slower than third separator cylinder  60 . In this adaptation, the doffing cylinder  55  may effectively doff the second separator cylinder  50 , and then itself be doffed by the third separator cylinder  60 . 
     To direct the flow of fiber removed from the second separator cylinder  50  by the first doffing brush  55  into engagement with the projections on the third separator cylinder  60 , a shroud or flow guide  66  may be provided between the pinch point  57  of the second separator cylinder with the first doffing brush, extending therefrom parallel to the periphery of the doffing brush cylinder  55  in the downstream direction of fiber flow to the third separator cylinder  60 . The third separator cylinder  60  is positioned adjacent to the first doffing brush cylinder  55  such that the outer peripheral surface of the brush is operably associated with and rotating in the same angular direction as the third separator cylinder  60 . Thus, after the cleaned fiber is removed from the second separator cylinder  50  the fiber flow is directed into contact with and engaged by the projections of the third separator cylinder  60 . The fiber on the third separator cylinder  60  is then carried across t-he cleaning bars  64  to remove any residual foreign matter, and then to second doffing brush cylinder  65  (or other pneumatic doffing mechanism) whereupon the fiber is removed and recovered. 
     In another alternative embodiment shown in FIG. 7, the second housing  24  is provided with a fourth or reclaiming separator cylinder  70  (with cooperating cleaning bars  74 ) for cleaning the material removed by cleaning bars  54  and retrieving fiber therein. This embodiment may be used alone (FIG. 7) or in combination with the third separator cylinder  60  and second doffing brush cylinder  65  of the above-mentioned alternative embodiment as shown in FIG. 8 or  9  and described in greater detail hereinbelow. Again, the construction of the fourth separator cylinder  70  and cleaning bars  74  may be substantially the same as described hereinabove for the second separator cylinder  50  and cleaning bars  54 . Further, while the use of a solid face doffing brush with short bristles is preferred, other conventional doffing brushes may also be used, or a doffing cylinder such as a saw or other separator cylinder, may also be substituted for first doffing brush cylinder  55  as described above. The position of the fourth separator cylinder  70  relative to the cleaning bars  54  is not critical provided the cylinder is positioned where it can engage the material as it falls or is removed from the cleaning bars. Thus the fourth separator cylinder  70  may be positioned directly below the cleaning bars  54  so as to contact material falling therefrom by gravity, or it may be positioned elsewhere in the housing with the material being transported or channeled thereto. However, the position of the fourth separator cylinder  70  relative to the first doffing brush cylinder  55  is critical. 
     The fourth separator cylinder  70  is positioned adjacent to the first doffing brush cylinder  55  such that the outer peripheral surface of the brush is operably associated with and rotating in the opposite angular direction as the fourth separator cylinder  70 . It is also understood that the outer tip speed of doffing brush cylinder  55  should be greater than the outer tip speed of the fourth separator cylinder  70 . In this embodiment, the single doffing brush cylinder  55  may be used to effectively remove cleaned fiber from two different separator cylinders, i.e., second cylinder  50  and fourth cylinder  70 . As shown in FIG. 7, fiber is removed from the fourth separator cylinder by doffing brush cylinder  55  and channeled along the periphery of the doffing brush cylinder by shroud or flow guide  76  to pinch point  57 . The fiber moves across or through pinch point  57  whereupon it is combined with the fiber removed from the second separator cylinder  50 . 
     While the fourth, reclaiming separator cylinder  70  may be used alone, in further alternative embodiments it may also be used in combination with the third separator cylinder  60 . In a first such combination shown in FIG. 8, third cylinder  60  (with cooperating cleaning bars  64 , and second doffing brush  65  or other pneumatic doffing means) and fourth cylinder  70  are each positioned as described in FIGS. 6 and 7, respectively. In this configuration, third and fourth separator cylinders function as described above, with the fourth cylinder  70  reclaiming fiber from the discarded material removed from second separating cylinder  50  by cleaning bars  54 . 
     In an alternative configuration shown in FIG. 9, fourth cylinder  70  may be positioned to engage and retrieve any fiber in the waste material removed from the third separator cylinder  60  by the cleaning bars  64 . In this embodiment, the fourth separator cylinder is located where it can engage the material as it falls or is removed from cleaning bars  64 . To provide for the doffing of retrieved fiber from the fourth separator cylinder  70 , the fourth cylinder is also positioned adjacent to the second doffing brush cylinder  65  such that the outer peripheral surface of the brush is operably associated with and rotating in the opposite angular direction as the fourth separator cylinder  70 . For use in this embodiment, second doffing brush cylinder  65  may be constructed in the same manner as described for the first doffing brush  55  in the embodiment of FIG. 7, and again, the outer tip speed of doffing brush cylinder  65  should be greater than the outer tip speed of the fourth separator cylinder  70 . As in the embodiment of FIG. 7, in this embodiment, the second doffing brush cylinder  65  may be used to effectively remove cleaned fiber from two different separator cylinders. However, in contrast to the embodiment of FIG. 7, the second doffing brush  65  in the embodiment doffs the fiber from third cylinder  60  and fourth cylinder  70 . 
     Thus, in overall operation, mixture  11  is introduced into the first separator in first housing  23  through inlet chute  27 . The introduction of mixture  11  may be in any suitable manner, such as gravity feeding, pneumatically, mechanically conveying, etc. 
     In the figures, the arrows inside each cylinder represent the direction of rotation of that cylinder, and hence the direction of rotation of projections and wipers attached thereon. Mixture  11  travels over the rotating cylinders and is propelled to the right due to the clockwise rotation of the cylinders. Some of the mixture may fall in between the rotating cylinders. Mixture  11  then passes around the right most cylinder, and is then propelled under the rotating cylinders and brought into contact between the cylinder projection and the concave separation structure  40 . 
     As mixture  11  is propelled under the revolving cylinders and against the discontinuous concave separation structure  40 , foreign matter  12  begin separating from mixture  11  and fall through spaces  43  into a transport duct for disposal, recycling, or further treatment. Mixture  11  continues moving through first housing  23  and by virtue of its transit past the multiple cylinder separation surface interfaces, gradually becomes a mixture consisting primarily of fibers and residual foreign matter. This intermediate mixture is propelled into the second separator in second housing  24  where even more foreign matter is separated out. 
     It is understood that the foregoing detailed description is given merely by way of illustration and that modifications and deviations may be made therein without departing from the spirit and scope of the invention.