Abstract:
The invention is an improved and environmentally-friendly animal bedding material, particularly useful as horse bedding. The bedding of the invention is generally non-irritating, substantially dust free flax shives which have an inner core and outer surface with sufficient inner core being exposed to make the bedding absorbent.

Description:
This application claims the benefit of U.S. Provisional Application No. 60/243,696, filed Oct. 26, 2000. 
    
    
     The invention is an improved and environmentally-friendly animal bedding material, particularly useful as horse bedding. The bedding of the invention is generally non-irritating, substantially dust free flax shives which have an inner core and outer surface with sufficient inner core being exposed to make the bedding absorbent. 
     BACKGROUND OF THE INVENTION 
     A number of different materials have been used as animal bedding, and in particular, horse bedding. Traditionally, horses and other animals have been bedded on straw. Despite its good availability, handling characteristics and disposability, straw has significant disadvantages, including low moisture absorbency, limited comfort for the animals, and high palatability that provokes herbivores to eat contaminated bedding. The low moisture absorption rate of straw bedding necessitates more frequent stall cleaning. 
     It has long been known that the bast fibers of various plant materials, e.g. flax, jute, hemp, ramie, kenaf, have particular utility in a wide variety of textile and, industrial uses. Accordingly, many different types of machines have been used to process the material for separating the bast fibers of the plant material from the woody portions thereof. For example, machines that utilize a scutching or beating or flailing action as the primary mechanism to break-up the woody material for dislodging it from associated fibers are well-known in the art. 
     The stalk of the flax plant has about 30-40% long outer bast fibers and 60-70% short woody inner core fibers or shives. The shives are left as a by-product when the flax material is processed to separate the fibers therefrom. Accordingly, the majority of the flax plant is left as a low-cost reject that is disposed of without any appreciable commercial gain such as by supplying it to farmers for livestock as an inefficient bedding, or for piling it along treelines as biomass to mix with soil and for stopping weed growth. In this regard, sale of shive material only takes in around $9 per ton or in otherwise burned as waste. 
     SUMMARY OF THE INVENTION 
     This invention relates to animal bedding material made from agri-by-products, such as flax shives, which are non-palatable for herbivores, including livestock and have a low composting rate. It is most particularly suited for use with horses and farm animals (livestock). The agri-by-products used in the invention are difficult to compost. Indeed, if these agri-by-products were not used in some fashion, they would be burned on the field contributing to Greenhouse gas emissions. 
     The flax shives which are included in the animal bedding composition of the invention have a specific particle size; are substantially without a residual seed content, which seed content (or lack thereof) will reduce the palatability of the shives to animals, e.g., herbivores and carnivores; and are substantially free of toxins, such as herbicides and pesticides; are substantially free of preservatives; and are substantially dust free. In general, the flax shives should have less than about 1 weight percent seeds, and in another aspect, less than 0.5 weight percent seeds. 
     Flax shives have a hydrophobic outer layer and porous inner core. The proportion of exposed inner core and outer surface of the shives used in the invention is carefully controlled to provide superior uniform water absorbency for the bedding composition. The absorbency is such that the bedding can absorb more than about 400 percent of its dry weight in water. The inner core of the shive is absorbent, hence, the amount of core that should be exposed to be effective for making the bedding absorbent, but sufficient skin or outer shive surface should remain to make the shives more durable to decomposition in the stall than cereal straw. In general the flax shives should have a length in the range of from about 0.2 to about 0.9 inches. Generally, the ratio of exposed inner shive core to outer surface of the shive particles ranges from about 4:1 to about 1:3. In another aspect this ratio is about 1:1. 
     The size and shape of each particle including length, width, and thickness is controlled to 0.2″-0.9″, 0.01″-0.03″, 0.01″-0.03″, respectively. 
     In another aspect, the shives of the invention are mixed and compressed with non-palatable materials such as flax, hemp, kenaf, ramie, sisal straw, and mixtures thereof to make a combination bedding. In this aspect the shives constitute at least 50 weight percent of the bedding, but may form 100% of the bedding. 
     In yet another aspect, the invention provides a method of providing bedding for an animal comprising spreading the bedding composition on a substrate surface, such as a barn floor or the ground. 
     The value of the invention is evidenced by the fact that the bedding product converts an agricultural waste product into a useful animal bedding composition and thereby also reduces Greenhouse gas emissions into the atmosphere by preventing burning of the agricultural waste material. 
     DETAILED DESCRIPTION OF THE INVENTION 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view of a plant material system for producing flax shives used in the invention; 
     FIG. 2 is a schematic view of an alternate plant material processing system in accordance for producing flax shives and showing various processing sections thereof; 
     FIG. 3 is an elevational view showing five sets of spiked cylinders and concave members followed by a pair of elevator cleaners each including six sets of rotors having finger projections extending radially therefrom; 
     FIG. 4 is an enlarged elevational view of a pair of spring loaded mat forming rollers upstream from a set of a spiked cylinder and associated spiked concave member showing the spikes of the concave member arranged upstream from a downstream grated section thereof; 
     FIG. 5 is a front elevational view showing the spikes on the cylinder member arranged in axial rows with spikes in adjacent rows being offset from each other; 
     FIG. 6 is a perspective view of the concave member showing plates having the spikes in axial rows thereon with spikes in adjacent rows being offset from each other; 
     FIGS. 7 a-   7   c  are front elevational views showing successive rows of spikes on the cylinder member being rotated through a scraping area defined by the overlap between the spikes on the cylinder and concave member; 
     FIG. 8 is an elevational view of one of the rotors and its radial fingers and an associated concave grated member; 
     FIG. 9 is a perspective view of the rotor and concave member of the elevator cleaner showing the radial fingers arranged in axial rows with fingers in adjacent rows being offset from each other; 
     FIG. 10 is a top plan view of an oscillating sieve section of a fiber recovery portion of the plant material processing system; and 
     FIG. 11 is a side elevational view of the oscillating sieve section of FIG. 10 showing a pair of sieves and a drive mechanism for oscillating the sieves. 
    
    
     DEFINITIONS 
     “Flax” as referred to in the present application refers to plant fiber crops being grown either for seed (i.e. linseed oil) or for its fiber or for both. Examples of such crops include  Lignum usitatissimum  (common flax),  L. usitatissimum  album (white-flowered flax), and  L. usitatissimum  vulare (blue-flowered flax). 
     The high quality fibers of flax are from the stem of the plant and are in the phloem or bast, hence, flax is described as “bast fiber” crop. As used herein, “bast” refers to those fibers from the phloem region. Further, as used herein, flax “shives” refers to the core tissue particles that remain after bast fibers are separated from the flax stem. Flax shives include blends and mixtures of all cell types including vascular bundles and parenchyma cells. 
     Substantially dust free means less than about 0.05 weight percent of particles having a particle size of less than 100 microns. 
     Substantially free of toxins means less than 1 ppm on weight bases of material toxic to animals. 
     Substantially free of preservatives means the bedding of the invention does not include any added ingredient for preserving the bedding where the ingredient is in an amount effective for preserving the bedding. 
     Flax Shives Used in the Invention 
     The shives which are included in the bedding composition of the invention have a specific particle size, are substantially without a residual seed content which reduced seed content and will reduce the palatability of the shives to the animal. The shives used in the invention are substantially free of toxins, such as herbicides, pesticides and preservatives, such as creosol. The shives used in the invention are substantially dust free. In general the flax shives should have less than about 1 weight percent seeds, and in another aspect, less than 0.5 weight percent seeds. In general, toxins should constitute less than 1 ppm of the shives. 
     In general the flax shives should have a length in the range of from about 0.2 to about 0.9 inches. Generally, the ratio of exposed inner shive core to outer surface of the shive particles ranges from about 4:1 to about 1:3. As previously described in another aspect, this ratio is about 1:1. 
     Generally, flax shives (as opposed to bast fibers) is supplied as at least about 95 weight percent shives. 
     The morphological nature and chemical composition of the flax shive influences and contributes to the properties and performance of the animal bedding. Shives have a hydrophobic outer layer or skin and a porous inner core. The core and skin and the ratio of exposed core to skin is very important to the invention. Moreover the shives should not include too much bast fiber because bast fibers may cling into animals feet. 
     The flax shives should not have a mean particle size of more than about 0.5 inches in length, and in an important aspect, the shives have mean particle sizes of from about 0.4″ to about 0.6″ in length and in another aspect, not more than about 20 weight percent of the particles are smaller than 0.4″. The shives used in the invention should have an average particle size distribution of from about 0.2″ to about 0.3″. 
     All chemical analyses and procedures were done according to the Technical Associate of the Pulp and Paper Industry (TAPPI) test methods as shown in Table 1. Flax shives used in the invention may be characterized chemically as set forth in Table 2. Generally, however, the shives used in the invention do not have more than about 24 weight percent lignin, and preferably less than about 20 weight percent lignin, and have more than about 70 weight percent polysaccharides. 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Chemical analysis and TAPPI test methods 
               
             
          
           
               
                   
                 Chemical Analysis 
                 TAPPI test methods 
               
               
                   
                   
               
               
                   
                 Moisture content 
                 T 258 om-85 
               
               
                   
                 pH of water extract 
                 T 252 om-90 
               
               
                   
                 Extractives 
               
               
                   
                 Hot water 
                 T 204 os-76 
               
               
                   
                 Alcohol-benzene 
                 T 204 os-76 
               
               
                   
                 Acetone 
                 T 204 os-76 
               
               
                   
                 Di-chloromethane 
                 T 204 os-76 
               
               
                   
                 1% sodium hydroxide 
                 T 212 om-88 
               
               
                   
                 Holocellulose 
                 T 212 om-75 
               
               
                   
                 α-cellulose 
                 T 203 om-88 
               
               
                   
                 Klason lignin 
                 T 222 om-83 
               
               
                   
                 Inorganic compounds 
               
               
                   
                 Ash 
                 T 211 om-85 
               
               
                   
                 Silicates 
                 T 245 om-88 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Chemical analysis of flax shives 
               
             
          
           
               
                   
                 Composition 
                 shive 
               
               
                   
                   
               
               
                   
                 Basic density, g/cm 3   
                 1 to 1.2 
               
               
                   
                 Moisture content, % 
                  7.5 
               
               
                   
                 pH of water extract 
                  6.5 
               
               
                   
                 Extractives 
               
               
                   
                 Hot water, % 
                  4.4 
               
               
                   
                 Alcohol-benzene, % 
                  2.1[0.1] 
               
               
                   
                 Acetone 
                  0.9 
               
               
                   
                 Di-cholormethane 
                  2.1[0.1] 
               
               
                   
                 1% NaOH, % 
                  28[1] 
               
               
                   
                 Holocellulose 
               
               
                   
                 α-cellulose, % 
                 38.6 
               
               
                   
                 β-cellulose % 
                 14.1[0.5] 
               
               
                   
                 γ-cellulose 
                 23.6[0.8] 
               
               
                   
                 Klason lignin, % 
                 19.0 
               
               
                   
                 Inorganic materials 
               
               
                   
                 Ash, % 
                  2.0[0.1] 
               
               
                   
                 Silicates, ppm 
                 737.5  
               
               
                   
                   
               
               
                   
                 Note: values for extractives are not additive.  
               
               
                   
                 [ ] - standard deviations  
               
             
          
         
       
     
     The absorbency of the animal bedding of the invention as compared to other known animal bedding is impressive as can be seen in the following example. 
     EXAMPLE I 
     (Absorbency) 
     Moisture Absorption 
     Five 10 gram unused dry (room: 20° C.±1° C., 50% room humidity±5%) samples of each bedding type are used. Each sample is placed in a beaker and weighed. A measured quantity of water is added to the beaker until visually water is seen to pool on top. The bedding is allowed to soak for 60 min. All excess water is displaced by inverting the beaker through a strainer for 60 minutes. The volume of the recovered water is measured and the beaker re-weighed. The water absorption properties of the different bedding materials are calculated and expressed as percentage weight gain and water absorbed. 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Amount of water absorbed for each bedding type. 
               
             
          
           
               
                   
                   
                 Water (ml) 
               
               
                   
                 Bedding 
                 absorbed/bedding 
               
               
                   
                   
               
               
                   
                 Invention (a) 
                 4 
               
               
                   
                 Invention (b) 
                 5 
               
               
                   
                 Straw 
                 2 
               
               
                   
                 Shavings 
                 3 
               
               
                   
                 Peat 
                 3 
               
               
                   
                 Hemp 
                 4 
               
               
                   
                 Pellets 
                 7 
               
               
                   
                 Paper 
                 10  
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Percent weight increase for each bedding type. 
               
             
          
           
               
                   
                   
                 Weight Increases 
               
               
                   
                 Bedding 
                 % 
               
               
                   
                   
               
               
                   
                 Invention (a) 
                 410 
               
               
                   
                 Invention (b) 
                 500 
               
               
                   
                 Straw 
                 225 
               
               
                   
                 Shavings 
                 254 
               
               
                   
                 Peat 
                 300 
               
               
                   
                 Hemp 
                 398 
               
               
                   
                 Pellets 
                 750 
               
               
                   
                 Paper 
                 900 
               
               
                   
                   
               
             
          
         
       
     
     EXAMPLE II 
     (Dust Assessment) 
     Dust samples from bedding were examined microscopically and graded according to the following categories modified from Clarke and Madelin (Equine Vet. J 19(5), 442-447 (1987)): 
     I. “Very Good”—Negligible quantities of mold spores present, the principal dust constituents being plant hairs, pollen grains and other plant and miscellaneous fragments. 
     II. “Good”—Mold spores present, primarily of the large-spored, “field fungi” types, e.g., Alternaria sp., Cladosporium sps. Small numbers of respirable spores, such as Penicillium sp. and Aspergillus sp., in the 2 to 5 μm size range may be present. A lot of plant material present. 
     III. “Poor”—A large number of mold spores present, primarily of the large-spored, “field fungi” types, e.g., Alternaria sp., Cladosporium sp. Small numbers of respirable spores, such as Penicillium sp. and Aspergillus sp., in the 2 to 5 μm size range may be present. Samples with evidence of a small amount of dust mite infestation are also included in this category. 
     IV. “Very Poor”—Consists primarily of large numbers of respirable spores. Occasionally the major constituents are actinomycete spores of approximately 1 μm diameter. Samples with evidence of heavy dust mite infestation are also included in this category. 
     Results—Particle Identification 
     
       
         
               
               
               
             
           
               
                   
                   
               
               
                   
                 Source 
                 Particle types and assessment 
               
               
                   
                   
               
             
             
               
                   
                 Invention 
                 Grade I 
               
               
                   
                   
                 Mainly plant particles present 
               
               
                   
                 Invention 
                 Grade I 
               
               
                   
                   
                 Mainly plant particles present 
               
               
                   
                   
               
             
          
         
       
     
     Particle identification of previously tested samples. (Note: assessment depends upon quality of individual samples analyzed). 
     
       
         
               
               
               
             
           
               
                   
                   
               
               
                   
                 Source 
                 Particle types and assessment 
               
               
                   
                   
               
             
             
               
                   
                 Straw 
                 Grade III 
               
               
                   
                   
                 Large amount of “field fungi” 
               
               
                   
                   
                 spores 
               
               
                   
                 Shavings 
                 Grade I 
               
               
                   
                   
                 Principally wood particles 
               
               
                   
                 Hemp 
                 Grade II 
               
               
                   
                   
                 “field fungi” spores 
               
               
                   
                 Pellets 
                 Range: Grade I-II 
               
               
                   
                 Paper 
                 Range: Grade 1-III 
               
               
                   
                   
               
             
          
         
       
     
     Making the Flax Shives Used in the Invention 
     The external portion of flax straw bales is manually stripped of wet sots and/or dirt as at  2 . The remaining portion of the flax straw bale is fed into a tub grinder  4  for initial bale breaking, straw shortening and crude fibre/shive separation. The partially separated flax straw is fed, via mechanical conveyor, to a bale opener  6  (opener) that aids in pulling apart tangles in the material. The partially separated and de-tangled material is then moved by air to a mote condenser  8 , the purpose of which is to remove dust and to create an even feed for the (STC&amp;C) spiked tooth cylinder and concave system  10 . The STC&amp;C unit  10  includes spiked cylinders and concave members which further separate shives and fibres. This material is then moved mechanically to an elevator cleaner or “XL” cleaner  12  for additional shive/fibre separation 
     The shive stream from the tub grinder, opener, mote condenser, the STC&amp;C unit and XL cleaner may be used in the invention. A shive stream having an exposed core to outer surface ratio of about 1:1 to about 3:1 come from the STC&amp;C unit and XL cleaner. The shive stream emanating from the tub grinder, opener and mote condenser has a ratio of exposed core to outer surface of about 4:1 to about 2:1. 
     All of the shive streams, plus fibre that has dropped out from the Opener, STC&amp;C and XL Cleaners during the cleaning process are conveyed on belts to an open-mesh screen vibratory conveyor (or sieve)  14 . The vibratory conveyor utilizes a shaking action to separate loose shives from fibre. The shives fall through the open-mesh screen and are carried mechanically to the top of an aspirated ball deck screener  16  that sorts shive particles into either one fraction of 0.2″ to 0.9″ in length or into two different fractions, of 0.5 to 0.9″ in length and 0.2 to 0.6″ in length. Air, generated by fans, is used to enhance particle movement and separation and to remove remaining dust. Dust may be removed using cyclones and fans. The shives are then sent to vacuum destoners  18  to remove the seeds therefrom. The de-dusted, destoned material is then fed, via auger, to a compression bagging machine. The product in the amounts of 50 lbs. is compacted to about 3.4 cubic feet. 
     An example of an alternate process for the production of flax shives is described in U.S. Pat. No. 6,079,647, which issued Jun. 27, 2000, which is hereby incorporated by reference, and in PCT/CA97/00511, published on Jan. 29, 1998 as WO98/03705, which is also hereby incorporated by reference. This process, which will be more fully described below and as seen in FIG. 2 et seq., is probably more rigorous in separating bast from shives used in this invention and also recovering bast fiber than is required for producing the shives used in this invention. However, after the alternate process, the shive product must be subjected to removal of seeds, e.g., by treatment with vacuum destoners. 
     In one form as can be seen in FIG. 2, a processing system is provided having a plurality of processing sections which separate the shives or woody portions from fibers of plant material and for reducing the size of the separated woody portions. These processing sections include a stripping section for exerting a pulling action on the plant material to strip shive or woody portions therefrom while minimizing damage to and shortening of the fibers. Following the stripping section, a cleaning section is provided for separating the majority of the remaining shives or woody portions associated with the plant fibers by scraping of the plant material to obtain a further separation of the remaining woody material for yielding a product that has a very high fiber purity with the scraping action similar to the stripping action, doing minimal damage to the fiber length so that the fibers remain at a length that is commercially valuable. 
     The alternate process system of FIG. 2 et seq. provides the provision of a cleaning apparatus for receiving decorticated plant material that has a first level of fiber purity, e.g. 55 to 60% fiber purity, and further separating remaining woody portions from fibers in the decorticated material to increase fiber purity to a second higher level of fiber purity, e.g. 90% fiber purity, over the first level. As seen in FIGS. 4-6, the apparatus includes at least one set of a cylinder and an associated concave member having a predetermined radial spacing therebetween and through which the plant material travels as the cylinder is rotated. Spikes are provided on the cylinder and the concave member that project generally radially therefrom and which are arranged so that the spikes overlap and are spaced laterally from each other as the cylinder is rotated and the spikes thereon pass the spikes on the concave member. Accordingly, as the cylinder spikes carry plant material past the concave member spikes, the material undergoes a scraping action to further remove any remaining woody portions from the fibers without substantial damage thereto. The spikes on the cylinder and the concave member are of a predetermined length that is slightly less than the predetermined radial spacing between the cylinder and concave member to minimize the radial clearance between the distal tips of the spikes and the cylinder and the concave member. By having the spikes extend to a depth close to the respective surfaces of the cylinder and the concave member, the amount of plant material in the lateral spaces between the respective spike members of the cylinder and the concave member undergoing the aforesaid scraping action is maximized. 
     Generally, there are five sets of cylinders and associated concave members provided through which the plant material travels. 
     The concave member can have a grated section that is downstream and circumferentially rearward of the concave member spikes in the plant material travel direction so that after the plant material carried by the cylinder spikes is subjected to the scraping action against the concave member spikes, the plant material travels over the grated section with scrapped off woody portions of the plant material passing through the grated section. The grated section has openings that are at a predetermined size selected to keep the longer fibers from passing through the openings while permitting the shorter scraped off woody portions to pass therethrough. 
     The processing equipment minimizes damage to the fibers so that they remain at a sufficient length for passing over the grated section, as otherwise proper sorting of fibers from separated woody portions will not occur potentially adversely affecting the subsequent processing of the plant material. Accordingly, the size of the grate openings is important for properly sorting the separated woody portions from the fibers for subsequent processing of the woody portions, as will be discussed more fully hereinafter. In this regard, the processing equipment utilized upstream from the cylinder and concave member keeps the fibers at a proper length so that the scraping action generated by the spikes of the cylinder and concave member do not shorten the fibers beyond their critical length for passing over the grated section. 
     The spikes of the cylinder and concave member generally are arranged in rows circumferentially spaced from one another with adjacent rows having spikes that are offset from each other so that the plant material is caused to undergo a back and forth scraping action as it is successively engages concave member spikes in different rows on either side of a particular cylinder spike. In this manner, the material is not continuously scraped along the same portion thereof throughout the spike overlap area and instead alternatively hits the offset spikes in different rows of the concave members at different times with different portions of the plant material to thereby minimize damage to the length of the fibers while still scraping off the woody portions therefrom. 
     The alternate method produces fibers from plant material by stripping woody material from fibers of the plant material to produce decorticated plant material at a first level of fiber purity, providing a plant material scraping area defined by cooperating spikes on a cylinder and associated concave member arranged in a set, feeding the decorticated plant material at the first level of fiber purity to the cylinder and concave member set, rotating the cylinder with the spikes thereon passing the spikes on the concave member with lateral spacing therebetween, carrying the decorticated plant material with the spikes on the cylinder to the scraping area by rotation of the cylinder, scraping woody portions of the plant material from the fibers as the plant material engages spikes on the concave member in the scraping area to minimize shortening of the fibers, and producing fibers at a higher level of purity than the first level after scraping and which are at a length that is only slightly shorter than the fibers fed to the scraping area. 
     The method may include arranging the spikes on the cylinder and concave member in circumferentially spaced axial rows with spikes in adjacent rows having spikes that are offset from each other, and causing the plant material to undergo a back and forth scraping action as the cylinder spikes carry plant material to the scraping area with the plant material successively engaging offset concave member spikes in different rows on the concave member on either side of a particular cylinder spike. 
     FIG. 2 depicts a plant processing system of the alternate method generally designated  100  which is designed to process very high-volumes of bast plant material, and preferably the flax straw that is grown in North America for its oilseed, to obtain the fibers therefrom at a commercially desirable length, and also to recover the shives. As shown, the plant or flax fiber processing system  100  includes a main flax fiber processing portion  120  of the system  100  which has processing sections with equipment that is designed to remove most of the fiber from the flax plant material. The flax processing portion  120  yields a product that has an approximately 90 percent fiber purity. 
     The processing system  100  also can include a woody or shive processing portion  140  for taking the shive separated in the flax fiber processing portion  120  and reducing its size to the size necessary for use in the invention. Further, a fiber recovery portion  160  can be provided preceding the shive recovery processing portion  140  for ensuring that substantially only shive material is fed to shive processing portion  140  and to retrieve any long fibers that may come out of stripping and cleaning sections,  200  and  220 , respectively, of flax fiber processing portion  120  of the system  100 . The flax fibers, recovered from the fiber recovery processing portion  160  are conveyed to a baler  1080  for being baled and stored. The shive that is sifted and falls through the baffles  1060  of the sieves  820  and  840  is conveyed to the grinding section  180  of the shive processing portion  140  of the processing system  100 . 
     The shive processing portion  140  of the system  100  preferably utilizes a rotary grinder section  180 , containing a pair of rotary grinders  770   a  and  770   b  to rapidly beat and grind the shive to a fine size. The grinders  770   a  and  770   b  are driven for high-speed rotation by a rotor drive  1140 . 
     The shive processing portion of the system  100  can also be provided with a rotary screening section  1400  downstream from the second grinder  770   b.  The rotary screening section  1400  contains cylindrical screens (not shown) through which the processed shive is screened, entering through the upstream open end  1440  and exiting from the lower downstream end  1460 . As shive particles sift through the screens, they fall into a hopper (not shown) and are conveyed into storage silos  1500 . The shive material that is not sifted through the screens is recycled back to the rotary grinders  770   a  and  770   b.    
     The stripping section  200  uses sets of fluted rollers  240  only shown schematically in FIG. 2 with sets rotating at progressively increasing operating speeds in the downstream direction. In this manner, a pulling action is exerted on the flax plant material which strips the shive therefrom with little damage caused to the fibers. The decorticating or stripping section  200  is effective to yield a product in the range of approximately 55-60 percent fiber purity and which is fed to the cleaning section  220  with the separated shives dropping out from the stripping section  200  between sets of rollers  240  for further processing. 
     The cleaning section  220  takes the product from the stripping section  200  and further purifies it to approximately 90 percent fiber purity, as previously-mentioned. To do this without causing substantial damage to the fibers, sets of cylinders  260  and associated concave members  280  are provided through which the plant material travels, and then to a pair of identical elevator cleaners  300 . The cleaning section  220 , and specifically the sets of cylinders  260  and associated concave members  280  are effective to scrape the flax as it is caused to travel therebetween against spikes  320  that are provided thereon. The scraping action is effective to separate the majority of the remainder of shives still attached to the flax fibers without too much shortening of the fibers. 
     Referring to FIGS. 4-6, the construction of the cleaning section  220  and particularly the cylinders  260  and concave members  280  thereof will next be described. The spikes  320  of the cylinder  260  are arranged in axial rows that are circumferentially spaced around the cylinder  260  and are fastened thereto as by a bolting arrangement  340 . Similarly, the spikes  320  of the concave member  280  are arranged in axial rows that are circumferentially spaced from each other. The concave member spikes  320  can be secured to individual plates  360  as by a bolting arrangement  380 . The cylinder  260  and associated concave member  280  are arranged at a predetermined radial spacing from one another with the spikes  320  being sized to extend radially so that distal tips  320   a  of the spikes only have a slight radial clearance from respective facing surfaces  260   a  and  280   a  of the cylinder  260  and concave member  280 . 
     Scraping areas  400  are defined between the cylinders  260  and concave members  280  in which the overlapping spikes  320  thereof are disposed and through which the flax plant material is caused to travel by rotation of the cylinder  260 . By having the spikes  320  extend to a depth close to the surfaces  260   a  and  280   a  of the respective cylinders and concave members  280  such that the overlap between the respective spikes  320  is maximized, the amount of plant material kept in the lateral spaces between the overlapping spikes  320  and undergoing the desired scraping action will also be maximized. By way of example, the spikes  320  can be approximately 3 to 3½ inches long with there being approximately a half inch clearance between the spike distal tips  320   a  and the surfaces  260   a  and  280   a.    
     Before the flax material is fed to the first cylinder  260  and associated concave member  280 , the flax is caused to travel through a pair of crush rollers  420  and  440  for forming a mat of flax material to be fed to the first scraping area  400  as carried by the spikes  320  on the cylinder  260  and to provide protection by removing foreign objects from the flax material. In this regard, the upper roller  320  can be spring loaded as by coil spring  460  so as to form a nip between the upper and lower rollers  420  and  440  through which the plant material is drawn. 
     For minimizing the damage done to the fibers of the flax material as it travels through the scraping areas  400 , the spikes  320  on each of the cylinders  260  and concave members  280  are arranged such that spikes in one row are offset in an axial direction from spikes in an adjacent row. In this manner, as the cylinder  260  is rotated, the flax material carried by a cylinder spike  320  will be scraped against the closest concave member spike  320  immediately adjacent thereto on one lateral side thereof. Continued rotation of the cylinder  260  causes the plant material spaced farther away from the cylinder spike  320  that carries it on both sides of this cylinder spike  320  to be scraped against concave spikes  320  that are equally spaced slightly further apart on either side of the cylinder spike  320 . Thereafter, plant material on the other side of the particular cylinder spike  320  will next scrape against the closest concave member spike  320  on that lateral side of the particular cylinder spike  320 . Accordingly, at different times as the plant material is being pulled through the scraping area  400  by the cylinder spikes  320 , the plant material on one side and/or the other of cylinder spike  320  and at different locations thereon will be undergoing a scraping action against an adjacent concave member spike  320  but not for the entire time the plant material is in the scraping area  400 . In this manner, the plant material is caused to undergo a back and forth scraping action on either side of a particular cylinder spike  320  as it is pulled thereby through the scraping area  400 . 
     This arrangement of spikes  320  in the scraping area  400  can best be understood by reference to FIGS. 7 a-   7   c.  As can be seen in these figures, the spikes  320  have tapered side surfaces that converge at their distal tips  320   a  so that there is somewhat of a mating arrangement as cylinder spikes  320  are rotated through the scraping area  400  and past concave member spikes  320  on either side thereof. As shown, the cylinder axial rows of spikes  320  can repeat every fourth row in terms of the axial positioning of the spikes  320  in a row. The concave member spikes  320  can be similarly arranged in terms of their axial offset so that they repeat every fourth row. In this regard, FIGS. 7 a-   7   c  show variations in the height of adjacent concave member spikes  320  despite all of the concave member spikes  320  having the same radial length. The variations in height shown in  7   a-   7   c  are because of the different rows in which the spike members  320  are disposed on the concave member  280  with the spikes  320  that appear shorter in height being disposed in rows that are more circumferentially downstream from the taller appearing spikes  320 . Accordingly, spikes  320  having the same height are all arranged in the same axially extending row. As such, it can be seen that the concave member spikes  320  like the cylinder spikes  320  repeat every fourth axial row in terms of their axial position within a row. 
     As previously discussed, the concave member spikes  320  are provided on individual plates  360 . The plates  360  are adapted to be mounted to arcuate frame members  480  and  500 . The concave member frames  480  and  500  are interconnected by transverse bars  520  which cooperate to form a grated section  540  that is circumferentially rearward or downstream from the concave member spikes  320  and the plates  360  to which they are mounted. The circumferential spacing of the transverse bars  520  of the grated section  540  is carefully selected so that the openings  520   a  formed therebetween are especially adapted for use in the flax processing system  100  herein. More specifically, the spacing  520   a  between the transverse bars  520  of the grated section  540  is selected to keep longer fibers that are scraped from the flax material in the scraping area  400  from falling through the openings  520   a  while permitting the shorter scraped off shive to fall therethrough. Preferably, the grate openings or spaces  520   a  between grate bars are sized to be on the order of approximately one half of an inch for the present processing system  100 . 
     For providing strength to the grate bars  520  so they do not flex during operation of the system  100  herein and to assist in travel of the longer lighter fibers of the flax material over the grate bars  520 , several circumferentially extending support or guide bars  560  can be attached between the bars  520  with the guide bars  560  being axially spaced from each other, as shown in FIG.  6 . In this manner, the lighter fibers which tend to wad or clump together can more readily be pulled over the grated section  540  by the cylinder spikes  320  with the heavier pieces of shive separated from the fibers falling through the grate openings  520   a  between the grate bars  520 , as shown in FIG.  4 . 
     To mount the plates  360  with the concave member spikes  320  thereon, the frame members  480  and  500  have channel rails  580  and  600 , respectively, formed on their facing inner sides so that the plates can be slid into position between the members  480  and  500  on the rails  580  and  600 . In the preferred and illustrated form, three such plates  360  are provided with the first or upstream plate  360   a  having three rows of offset spikes  320  thereon and downstream plates  360   b  and  360   c  having two such offset rows of spikes  320  thereon. With the upstream plate  360   a  bolted or clamped in place relative to the frame members  480  and  500 , the downstream plates  360   b  and  360   c  will be held and captured in place on the rails  580  and  600 . Should less of a scraping action be desired, the scraping area  400  can be altered as by removing one of the plates  360  and replacing it with a blank, such as one of the plates  360  with the spikes  320  unbolted and removed therefrom. In this manner, the concave member  280  affords the option of adjusting the precise scraping action that the plant material undergoes in the scraping area  400 . 
     The cleaning section  220  is provided with five sets of cylinders  260  and associated concave members  280  through which the plant material travels with downstream cylinders  260  and concave members  280  being slightly vertically higher than the preceding, upstream cylinder  260  and concave member  280 , as can be seen in FIG.  3 . The cylinder  260  is rotated at a predetermined speed that causes the material to travel through the scraping area  400  and out past the grated section  540  at a threshold speed that is sufficient to deliver it to the next cylinder  260  and associate concave member  280  downstream therefrom by the momentum imparted thereto by the immediately upstream cylinder  260 . It has been found that rotation of the cylinder  260  at approximately 500 to 1100 rpms where the cylinder  260  is approximately 30 inches in diameter provides the material with sufficient momentum for being delivered to an adjacent downstream cylinder  260  while keeping a long fiber length and providing a high throughput for the large volume of flax material that the present system  100  is designed to process. The cylinder  260  and concave member  280  can be similar to that used in the 9600 John Deere combine used for processing rice with modifications as described above so that they are adapted for use in the present flax plant processing system  100 , and particularly the flax fiber processing portion  120  thereof. 
     After the flax plant material has exited from the last set of cylinder  260  and associated concave member  280 , it is fed to the pair of elevator cleaners  300  which exact a further separation of any loose shive pieces in the material that has been processed through the scraping areas  400 . Each elevator cleaner  300  can include several rollers or rotors  620  which have very long radially extending fingers or rods  640  that are bolted or otherwise rigidly secured thereto and project radially therefrom so that there is only a slight clearance between their distal tips  640   a  and concave members  660  The concave members  660  each include a grated section  700  thereof formed by axially extending grate bars  720  that are circumferentially spaced to form grate openings  720   a  therebetween. Similar to the grated portion of the concave member  280 , the grate openings  720   a  are sized to permit only the short shive pieces to pass therethrough with the longer fibers being carried by the fingers  640  for travel thereover. Generally, the grate openings or spaces  720   a  between grate bars  720  are sized to be on the order of approximately one half of an inch. The fingers  640  are arranged in axial rows with fingers  640  in adjacent rows being axially offset from each other. As shown, the rows of fingers  640  preferably repeat every other row. The fingers  640  act to pick the flax material and drag it over the grated section  700  thereby dislodging any loose shive from the longer plant fibers. 
     The fingers or rods  640  can be provided with an annular grove  740  adjacent their rigid attachment to the rotor  620 . The grooves  740  allow the fingers  640  to break thereat if the fingers  640  encounter excessive force such as could occur if can excessive amount of flax fibers wad together. Instead of the wadded flax fibers being pushed against the concave grated section  700  and potentially bending and damaging this part of the elevator cleaner  300 , the break-away grooves  740  cause failure in only the stressed fingers  640  which can be easily replaced versus the concave members  660 . Further, this allows the elevator cleaner  300  to continue to function properly without varying the small radial clearance, e.g. on the order of 0.025 inches, through which the plant material travels. 
     As shown, each elevator cleaner  300  generally has six sets of rotors  620  and concave members  660  that are arranged at increasing vertical heights with respect to the immediately upstream rotors  620  and concave members  660  so that the elevator cleaner  300  causes the plant material to travel at a pitch of approximately 45.degree. upward until it exits therefrom. By way of example, the rotors  620  can have a 6⅝ inch diameter with the fingers  640  being approximately 8 inches long. To provide the flax material with sufficient momentum for feeding to an upstream rotor  620  and concave member  660 , the rotors  620  can be rotated in the range of 100 to 700 rpms, and most preferably are rotated at approximately 500 rpms. 
     After the plant material has been processed through the cleaning section  220  including, the five sets of spiked cylinders  260  and associated concave members  280 , and then the two elevator cleaners  300  each including six sets of rotors  620  and concave members  660 , the product yielded therefrom will be at approximately 90 percent fiber purity while at the same time keeping the fiber length at the size necessary for commercial use despite the relatively tough and small size of the oilseed flax straw which the system  100  processes. After the fiber leaves the final downstream elevator cleaner  300 , it is conveyed to a baler  760  where it is baled and stored. 
     The fiber recovery portion  160  of the system  100  has a sieve section  810  utilizing a pair of oscillating sieves  820  and  840  (see FIGS.  10  and  11 ). Turning now to FIGS. 10 and 11, drive shaft  1040  of the drive mechanism  860  is connected to the pivot links  880  and  900  eccentrically so that it drives the pivot links  880  and  900  in an orbital back and forth path which causes the horizontal sieve  820  and  840  to oscillate both horizontally and vertically in a 2:1 ratio so that for every two inches the sieves  820  and  840  are caused to move horizontally, they are cause to move one inch vertically. The pivot links  880  and  900  are pivotally attached to respective pivot mounting bars  920  and  940  at one of the ends thereof with the mounting bars  920  and  940  being pivotally mounted to fixed mounting blocks  960  and  980  at their other ends for the sieves  820  and  840 , respectively. The mounting bar  920  is fixed to the downstream end  1000  of sieve  820  intermediate pivotally mounted ends of the mounting bar  920 . The mounting bar  940  is fixed to the upstream end  1020  of sieve  840  intermediate pivotally mounted ends of mounting bar  940 . In addition, the oscillating movements of the sieves  820  and  840  are coordinated so that they move in equal and opposite directions at the same time such that if sieve  820  is moving back in an upstream direction, the sieve  840  is moving forward in a downstream direction; and if sieve  820  is moving vertically downward, sieve  840  is moving vertically upward. In a like manner, if the sieve  820  is moving in a downstream direction, the sieve  840  will be moving back in an upstream direction; and if sieve  820  is moving vertically upward, the sieve  840  will be undergoing a vertically downward motion. The opposite oscillating movements of the sieves  820  and  840  tend to cancel out one another in terms of the momentum imparted to the plant material thereon thus keeping it on the screen surfaces of the sieves  820  and  840  for a longer period of time for screening out the heavier shive in the flax plant material through the sieves  820  and  840  as they are being oscillated. In this manner, the oppositely oscillating sieves  820  and  840  serve to shake loose the separated shive material from the flax fibers which tend to clump together as a consequence of the shaking action and thus will not fall through the sieves  820  and  840  so that substantially only shive is delivered to shive processing portion  140  of the present flax processing system  100 .