A METHOD OF FIBRE SEPARATION FIELD OF INVENTION This invention relates to a method and/or apparatus for the separation of asymmetric particles, including fibres, filaments, gels and long-chain molecular structures including polymers. It has particular application to the separation of cellulosic fibres for use in the production of paper either from a single fibre resource, from a fibre mixture, or from waste or recycled paper.

BACKGROUND Paper is made from a wide range of cellulosic fibres. The various paper strength, surface and optical properties are achieved by the optimum selection of the fibres and their subsequent pre-treatment before paper-making. Fibres may be recycled or new fibres. Various new fibres may be obtained from different tree or plant species and various fibre properties may be achieved by preselecting the pulping process (chemical or mechanical processes) and subsequent refining operations. In New Zealand a further innovative option is used: separating and pulping the wood from the top of the tree, and also pulping separately the outer slabwood from the bottom of the tree log.

The fibres are liberated from wood chips and dispersed in water as a suspension. There are two processes used to separate fibres in water suspension or remove unwanted materials and the obtain various fractions. These are the two hydrodynamic processes of screening and hydrocycloning. The wide diversity of lengths, diameters, fibre flexibility, and fibre surface fibrillation within the fibres have limited the success of these processes in separating or enriching a fibre stream. The separation difficulties are further heightened as the density differences of the fibres are extremely small and their surface differences are not excessive.

OBJECT OF INVENTION It is an object of this invention to provide an improved method for the separation of asymmetric particles and in particular wood pulp fibres, or to at least provide the public with a useful choice.

STATEMENT OF INVENTION Accordingly in one aspect the invention may be said to comprise a method for the separation of fibres wherein a majority of the fibres are aligned substantially parallel to each other; and said aligned fibres are moved relative to one or more solid edges, so that a first fraction of the fibres are transiently retained on said solid edges and a second fraction of the fibres are not retained on said solid edges.

Preferably there may be more than one edge.

Preferably the relative motion of said fibres and edges may cause some fibres to bend around said edge. More preferably the relative motion may be such that the flexible and/or long fibres bend about the edge and less flexible and/or short fibres pass by said edge.

Preferably it may be possible to alter the relative velocity at which the fibre and edges meet so that fibres of specific flexibility or length may be caused to impinge.

Preferably said impinged fibres may bend around the edges and be transiently retained upon said edges.

Preferably said edges may be moved relative to the source of the fibres.

Preferably said transiently retained fibres may be removed from the edges to form a first fraction. More preferably the non-retained fibres may be isolated to a second fraction.

Preferably said fibres may be cellulosic. More preferably said fibres may be wood pulp fibres for paper-making, or they may be recycled fibres or a combination of new and recycled fibres.

Preferably the fibres may be in a suspension or slurry.

Preferably the fibres in the suspension or slurry may be caused to align substantially parallel to each other by a deceleration in the flow rate of said slurry or suspension.

More preferably the majority of said fibres may be caused to align substantially parallel to each other and substantially perpendicular to said edges before impinging on the said edges.

Preferably the edges may be able to move relative to the source of the fibres. More preferably such movement may allow the transiently retained fibres to come in contact with a removal means. More preferably said removal means may remove the transiently retained fibres from the edges to a first fraction.

Preferably the edges may be capable of returning to their initial position relative to the source of the fibres after the transiently retained fibres have been removed.

Preferably the flow of the fibres, their impingement and subsequent removal may be a continuous process.

In another broad aspect the invention may be said to consist of an apparatus suitable for the separation of fibres or filaments into two or more fractions, comprising: means for aligning fibres; separation means; means for creating relative movement and collisions between the fibres and separation means; and means for removing fibres from the separation means.

Preferably the means for aligning the fibres may align the fibres substantially parallel to each other. More preferably the fibres may be aligned substantially perpendicular to the separation means.

Preferably there may be means of separating the fibres on the basis of their flexibility or length. More preferably these means may comprise at least one edge capable of collecting at least some of the fibres. More preferably the separating means may comprise a plurality of edges.

Preferably the means for creating relative movement and causing collisions between the fibres and the edges may involve moving either component towards the other. More preferably said movement may be at sufficient rate to allow stapling or bending of at least some of the fibres.

Preferably there may be means of moving the separation means relative to the source of the fibres. More preferably the separation means may be capable of moving from an area where the fibres are capable of impinging on the edges to an area where they are not. More preferably said movement may present a new set of edges for fibres to impinge upon allowing the separation of fibres, when the apparatus is in use, to be a continuous process.

Preferably, the removal means may allow the removal of the impinged fibres from the edges of the separation means. More preferably the removal means may comprise a plurality of washes, brushes, or fans, or a type of doctor blade.

Accordingly in another aspect the invention may be broadly said to consist of an apparatus for the separation of fibres for paper-making, wherein said apparatus comprises means for introducing suspended fibres to a solid surface; said surface having a plurality of edges and being configured such that flexible or long fibres may staple and be transiently retained on said surface edges; said apparatus also comprising a series of streams interspersed between said edges so that less flexible fibres are able to pass by said surface to a first reservoir ; removal means for removing transiently impinged fibres from said solid surface; and localising means for localising the flexible fibres into a second reservoir.

Preferably the introduction means may comprise at least one injector mechanism.

Preferably the injector mechanisms may have means for controlling the flow rate of the suspension to the solid surface.

Preferably the injector may be capable of decelerating the suspension prior to its introduction to the moving solid surface, so that the fibres may be presented in a decelerating flow field.

Preferably the injector means may be capable of accepting a distributor means to vary the area to which the suspension flows.

Preferably the fraction containing the less flexible fibres can pass through the series of stream in to the first reservoir.

Preferably the moving solid surface may comprise a plurality of discs or wires. More preferably the discs or wires will be arranged substantially parallel to each other.

Preferably the discs or wires may be oriented such that the suspended fibres may impinge on the edges.

Preferably the discs or wires may be arranged to form a substantially cylindrical shape.

Preferably the movable solid surface may be adapted for rotation about an axis extending laterally along the centre of the cylinder.

Preferably the movable solid surface may be adapted for rotation relative to the introduction means, the removal means, the localising means and the reservoirs.

More preferably the introduction means, the removal means, the localising means and the reservoirs may be in a substantially fixed position relative to each other.

Preferably the movable solid surface may be adapted for rotation such that the edge upon which the stapled fibres are transiently upon may move to a second position wherein there are means for removing the stapled fibre to the second reservoir.

Preferably the localising means may comprise at least one shunt, splash guard or deflector plate. More preferably the localising means may comprise a plurality of shunts, splash guards or deflector plates.

Preferably the means for removing the fibres from the edges of the moving solid surface may comprise a plurality of washes or brushes.

Preferably the removal means may be positioned in such a way relative to the localisation and introduction means that the removed fibres are localised to the second reservoir.

In a further aspect the invention may be broadly said to relate to an apparatus, useful in the separation of wood pulp fibres, substantially as herein described with reference to any of the examples.

In a further aspect the invention may broadly be said to relate to a method of separating wood pulp fibres on the basis of flexibility and/or length or more long and short fibres and creates two separate fractions enriched for either the more flexible or less flexible fibres, wherein the method comprises the steps: a. Introducing suspended wood pulp fibres against a solid surface; said surface having a plurality of edges being configured such that more flexible and/or longer fibres staple and are transiently retained on said surface edges; and less flexible fibres and/or shorter are able to pass by said surface into a first reservoir; and

b. Rotating or translating said edged surface relative to the suspension source so that the stapled flexible fibres are not dislodged from the edge surface by the proceeding fibres; and c. Removing the impinged fibres from said solid surface into a second reservoir; and d. Rotating or translating said edge surface further so that it completes either a 360° rotation or returns the said edged surface to the starting position, and in so doing delivering more impinged fibres to the removal site.

Preferably the suspended wood pulp fibres may be introduced to the moving solid surface by one or more injector mechanisms.

Preferably the flow rate of the suspended fibres may be regulated to suit the desired flexibility or long of the selected fibres.

Preferably the solid surface may comprise a series of edges of such a width that flexible or longer fibres may staple and be transiently retained.

Preferably the edges may be substantially parallel to each other.

Preferably the impinged fibres may be removed from the edges either by a plurality of washes, brushes, or doctor blades.

Preferably the less flexible and/or shorter fibres may be prevented from entering the second reservoir by one or more splash guards, shunts or deflector plates.

Preferably the separation process is continuous.

In yet a further aspect the invention may broadly be said to comprise the methods for separating wood pulp fibres in the basis of their flexibility or stiffness and/or length, using the apparatus substantially as herein described.

In yet a further aspect the invention may broadly be said to comprise the method for separating wood pulp fibres on the basis generally of their flexibility or stiffness or length, substantially as herein described with reference to any of the examples. There could be other

factors that aid in momentary retention such as fibre surface roughness due to fibrillation or fibre refining, or fibre defects such as kinks, knee-joints and fibre damage.

This invention may also be said to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more parts, elements or features, and where specific features are mentioned herein which have known equivalents such equivalents are deemed to be incorporated herein as individually set forth. A number of different examples will be described hereafter, some with moving edges, some where the injector (s) move relative to the solid edges.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic drawing of one example of a conduit and distributor arrangement.

Figure 2 is a plan of Example 2 of the apparatus from an end on perspective.

Figure 3 is an illustration of fibres bending or stapling about a wire of example 2.

Figure 4 is a more detailed side view of the apparatus in Example 2 that may be used to perform the method herein described Figure 5 is a side on view of the apparatus described in Example 2 that may be used in performing the method in described herein.

Figure 6 displays a view of a possible frame which the apparatus described in Example 2 may include.

Figure 7 is a close up view of the ribs featured in the apparatus of Figure 6.

Figure 8 shows the relative distance between the wires of Example 2.

Figure 9 highlights the internal members of the drum structure of Example 2.

Figure 10 provides a side on view of the apparatus described in Example 3 for performing the method described herein.

Figure 11 provides a close up view of the disc edge.

Figure 12 illustrates the apparatus of Example 3 which can be used to perform the method of the invention.

Figure 13 illustrates a possible removal means, for employment with the disc apparatus of Example 3.

Figure 14 illustrates a possible complete apparatus combining Examples 1 and 2 3.

Figure 15 front view of complete apparatus combining Examples 1 and 2 or 3.

Figure 16 is a photographic representation of a frame for joining Examples 1 and 2 together.

Figure 17 illustrates photographically a combination of Examples 1 and 3 together with a frame.

Figure 18 is a schematic of the apparatus described in Example 5.

Figure 19 is a close up schematic of the upper drum structure of Figure 18.

Figure 20 is a side on view of the apparatus described in Example 5.

Figure 21 is a top view of the apparatus described in Example 6.

Figure 22 is a side on view of the apparatus described in Figure 6.

Figure 23 illustrates a close up of the edges and ribs.

Figure 24 illustrates a further view of the apparatus described in Example 6.

Figure 25 is a graph illustrating the comparisons between different species of wood fibres and their characteristic distribution.

Figure 26 illustrates the variation amongst various species within the underflow.

Figure 27 graph of fibre length distribution in various feed samples.

Figure 28 graph of modified fibre length distribution.

Figure 29 illustrates differences between the characteristics of length and coarseness in treated and untreated fractions.

PREFERRED EMBODIMENT The following examples are given by way of illustration only and shall not be taken as being in any way limiting as to the spirit or scope of the invention. More particularly while the examples refer specifically to wood pulp fibres suspended in a liquid, the invention is in no way limited to that scope and could include other fibrous elements in fluid suspension.

This new method offers another means of potential separation for fibres, not primarily by surface area or length to diameter ratio, but by a new mechanism using the inherent fibre flexibility and length differences.

Wood pulp fibres are essentially hollow cylinders with sealed ends. They vary in average length from approximately lmm for hardwoods and 2.5mm for softwoods, although some fibres are as long as 5 to 6mm. Their'diameters'or widths vary considerably from 15 to 40ßm. However, their cell wall thicknesses vary also, not only from specie to specie, but also from tree to tree and across a growth ring. This variation in thickness changes the fibre stiffness or flexibility as well as the extent to which the cell walls collapse on drying. This is extremely important in paper-making as the collapsed fibres are more conformable in forming and drying and give a denser and stronger paper sheet. The collapsed fibres can wrap around each other and create a greater bonded area.

An improved approach to separation of fibres is to use the variation in flexibility (stiffness) and/or length of fibres flowing suspension. Preferably the fibres are allowed to impinge on a moving solid surface which allows the fibres momentarily to"staple"and adhere on the surface and then be removed from the flow field. The bulk of the liquid, fines and small fibres can pass by the solid surface to be removed as a separate stream. Fibre enrichment occurs leading to a preferential increase in fibres of different properties in both the accepts (overflow) and rejects (underflow).

"Staple"in this specification is taken to mean the bending of fibres around the solid surface edges and their transient retention on that surface."Adherence"could be due to stapling or

momentary entrapment on the solid surface which may or may not be either smooth or continuous.

A preferred method of the invention involves two main steps: 1. The first is causing the fibres to preferentially align so that they are substantially parallel to each other. This may be achieved with fibres in suspension by presenting the fibres in a decelerating flow field. This is described under the heading Example 1 and is illustrated by Figure 1. It is desirable but not mandatory that prealignment occurs.

2. The second is the collision of the aligned fibres with edges. A fraction of the fibres will bend around the edges or be caught momentarily while others that will pass by them. This is described under the heading Example 2 and Example 3.

EXAMPLE-1 Figure 1 illustrates a general mechanism which allows the deceleration of the fibres in suspension. The mechanism has the suspension passing from a conduit 10 with restricted area (Al) and a rapid flow rate (Ul) to a flattened fan shaped distributor 11 with an area (A2), much larger than A,. The flow rate (U2) of the suspension in this larger area (A2) is much less than that of Ul. The fibres 12 thus decelerate. Area is calculated by a cross-section of the conduit and the distributor. The flow rate is a product of the cross sectional area A and flow velocity U and hence as A increases the U value decreases.

Thus an increase in the size of the area to which the suspension of fibres are conducted, will result in a corresponding decrease in flow rate.

This deceleration is important as it changes the flow of the fibres and tends to cause the fibres to align substantially parallel to the lip 13 of the distributor 11. Thus the fibres 12 can be presented to a series of edges (not shown in Figure 1) in preferred orientation such that the fibres 12 are substantially perpendicular to the edges.

EXAMPLE-2 This example together with Example 3 describe two options with respect to the next step in the method and describes the arrangement of the edges and the related separation of the fibres.

With reference to Figure 2, the plurality of edges is formed by a series of wires 15 which together combine in a drum shaped structure 16 (see Figures 5 and 9). The centre of the drum 16 has a splash guard 17 located within its centre. Within this centre also runs a core 34. In this example the drum is capable of rotation relative to the distributor 11. The fibres are sprayed from the distributor 11 towards the edges. Some fibres will bend around an edge and be transiently held, others will pass by the edge. Those fibres that pass by the edge 15 are carried to form a first fraction. The bent fibres are carried by the rotating edge 15 over the splash guard 17 where they are removed to form a second fraction. The fibres may be removed by washing or as illustrated in this figure by one or more brush doctors 19.

Figure 3 illustrates a fibre 12 bending or stapling against the edge, in this version the edge is provided by a wire 15.

Figure 4 provides a detailed side view of Figure 2.

The conduit 10 is attached to a distributor 11 which decelerates the fibres causing them to align substantially perpendicular to the edges (see Figure 1). The edges are formed by a series of wires 15 which are arranged so as to form a hollow drum shape 16 (see Figure 5), with the wires 15 forming the surface thereof. The wire may be wound in a helical pattern along the length of the drum 16 or it may be that each edge represents a separate piece of wire.

The distributor 11 aims the decelerated fibres towards the series of edges 15. The deceleration causes the fibres to align substantially perpendicular to the edges 15. This enables some of the fibres to bend around the wire 15 and be transiently retained on the wire surface.

The wires are able to rotate so that the bent fibres 20 are carried over the level of the splash guard 17. The removal means in this illustration is a simple wash 21. The splash guard 17 ensures that the non-stapled fibres proceed to a first fraction 23 and the bent fibres proceed to

a second fraction 24. The splash guard 17 is retained in the correct orientation by a weighted lower portion 22 but is otherwise generally rotatable.

Figure 5 displays the wires 15 as being substantially parallel to each other, and co-operating so as to form a drum shaped structure 16. It also illustrate the presence means to rotating the wires 15. In this illustration the rotating means is a crank 30.

Figure 6 illustrates the frame that may be used in conjunction with the mechanism of Example 2. There are supports 31 at the end of each drum structure. These have legs 32 and a strengthened rotatable hollow 33 for accepting a core 34 which inserts down the centre of the splash guard. The frame also possesses a series of ribs 35 which extend from the rotatable hollow 33 at one end along the length of the drum to the rotatable hollow 33 at the other end of the drum 16. As shown in Figure 7, each of the ribs 35 have notches 36 to accept and retain the wires at the correct separation distance. Figure 8 shows the 5mm diameter wires 15 are retained approximately 10 mm apart.

Figure 9 illustrates how the splash guard 17, drum 16, and core 34 fit together. The splash guard hangs freely due its lower portion 22 being weighted.

EXAMPLE-3 Figure 10 illustrates Example 3, this is an alternative to Example 2.

The plurality of edges is formed by a series of outer discs 40 arranged substantially parallel to each other and forming an approximate drum structure 16. Interspersed between the discs are a series of cleaning belts 41, and a series of inner discs 42. These inner discs have a number of uses. These uses include: separating the outer discs 40 at a specific distance and acting analogous to the splash guard in the previous example; and preventing the remixing of one fraction to another. The belts 41 are there to provide a cleaning mechanism. The removal means are the same as for the previous example and in this illustration are a series of brush doctors 43.

As in the previous example the distributor 11 sprays the fibres at the discs 40,42 causing some fibres to bend around the edge of the outer discs 40 and be transiently held, others will

pass by the edge. The fibres which pass the edge can be carried to a first fraction and the bent fibres are transiently held and are carried over the edge and removed to form a second fraction.

The outer discs 40 are between 0.3 mm and 1.0 mm thick. Although the preferred thickness depends on the type of fibre and their prehistory. They have a diameter of 300 mm in this prototype but this will vary with the fibre source and desired fractionation. Their edges are preferably smooth, and preferably rounded (as shown in Figure 11) but may be serrated, knurled or sharp edged. In this example the drum 16 contains 60 of these outer discs 40.

The inner discs 42 or spacers are 2.5 mm thick but the spacing depends on the fibre source and the desired fractionation, and have a diameter of 200 mm. There are 59 of these inner discs 42. These inner discs 42 aside from acting as spacers also act analogously to the splash guards of Example 2. Between each of the discs is a nylon cleaning strap 41 of 2 mm or greater. The inner core has the same dimensions as that of Example 2.

Figure 12 displays the inner core 34. The core has a locking thread 44 onto which a large nut 45 can be placed so as to secure the discs 40 and 42 in place close together. Figure 12 illustrates how the different components fit together.

Figure 13 illustrates a possible means of removing the stapled fibres from the outer disc edges. This comprises a series of brushes 46 running along the doctor blade which exists over the entire length of the drum 16. The brushes 46 are arranged so that the captured fibres may be subsequently removed. Ideally the design would be such that the fibres can be removed from the brushes without interrupting the selection of the fibres. The discs are thereby cleaned so that they can pick up subsequent fibres.

EXAMPLE-4 This relates to a frame for joining Example 1 and either 2 or 3 together. Figures 14 and 15 illustrate how a frame can be made to include the conduit 10 and the distributor 11 together with the features of examples 2 and 3. The length the distributor 11 must span is 600 mm.

The conduit 10 is located slightly higher than the drum. The distributor 11 extends to fall just short of the drum. This position allows the fibres to pass or staple on the edges. Figures 16 and 17 illustrate photographically examples of such frames.

EXAMPLE-5 Figure 18 illustrates another example of an apparatus for performing two primary objects of this invention. The conduit 10 and the distributor 11 are present although in a modified form. The distributor 11 has an arc fan shaped appearance. In this example however the deceleration is obtained not only by the increased area of the distributor 11 over the conduit 10 but also by the location of the conduit below the lip of distributor 13. The deceleration results in a fraction of the fibres being substantially parallel to the lip 13 of the distributor 11 and substantially perpendicular to the plurality of edges 50.

The plurality of edges 50 consist of wires or polymers wound between two drum structures 51,52. The longitudinal length of said drum structures 51,52 runs substantially parallel to the lip 13 of the distributor 11. The drums 51,52 are arranged so that one drum 51 is below the level of the lip 13 and one drum 52 is above the level of the lip 13. The plurality of wires 50 run between the two drums in a plurality of individual loops or they may be continuous along the longitudinal length of the drums 51,52. In this example the upper drum 52 is rotatable along its longitudinal length so that the wires 50 are caused to travel in a continuous circuit between the two drums 51,52. The apparatus further features a smaller drum structure 53 which has a decreased circumference from the other drum structures 51,52, but runs longitudinal length of those other drum structures 51,52. This smaller drum structure 53 has a dual purpose of acting as a splash guard and maintains the correct tension on the wires so keeping them taut (sp).

In operation the fibres in suspension would pass from the conduit 10 to the distributor 11.

The deceleration in passing upwards through the distributor 11 will cause a fraction of the fibres to align substantially parallel to the lip 13 of the distributor 11 and substantially perpendicular to the plurality of wires 50. The continuation of the passage of the fibres past the lip 13 of the distributor 11 towards the wires 50 will allow some fibres to impinge upon the wires 50 and other fibres in suspension to pass between the wires into a first fraction.

The smaller drum structure 53 acts as a splash guard in this instance preventing the passage of the fibres into a second fraction. The impinged fibres will be carried on the wires 50 towards the upper rotatable drum 52. The fibres are carried away from the fibre stream and towards a removal means (not shown). The continuous nature of the wires 50 means that a fresh set of wire is exposed upon which a fraction of fibres from the fibre stream can

impinge. Once the fibres reach the removal means running along the length of the rotatable drum 52 (not shown), they are removed from the wires 50. This allows the wires to continue their circuit back to their starting position via the lower drum 51. The previously impinged fibres are removed to a separate fraction. The removal means in this apparatus are not illustrated but may comprise one or more brush doctors, brushes, or washes. The drums 51, 52, 53 may be solid hollow or may comprise a series of discs. Additionally as in prior examples they may just comprise a series of ribs around which the wires can be arranged.

Figure 19 illustrates a drum and further illustrates how the wires 50 may be held in place by a series of notches 55. Such notches may also be present on all the drums 51,52,53.

Figure 20 displays the relative arrangement of the two larger drums 51,52 and the wire 50 threading between them. It also displays how the smaller drum 53 increases the tension on the wires 50 and causes the wires to indent on their return passage towards the lower drums.

Figure 20 illustrates the relative locations of the distributor 11 and the smaller drum 53 which illustrates how it may be an effective splash guard, and prevent the fines and non stapled fibres from passing through to the second fraction.

EXAMPLE-6 Example 6 illustrates an alternative to the previous examples. Figure 21 illustrates the top view of the apparatus in Example 6. There is a plurality of edges 60 like the previous examples. However, these edges are located surrounding the source of the fibre stream 61.

As you can see from Figure 21 there is a plurality of sources in this model. The edges 60 or the plurality of sources 61 may be rotatable in respect of each other. Figure 22 displays a side view which shows the edges 60 and one of the fibre sources 61 within the middle of the continuous ring of edges. As can be seen from this illustration the fibre source 61 has an increased area through extending down the length of the stack of edges 60. As can be seen by Figure 23 the edges may comprise a series of discs 60 with their centres removed. Each of these is held in place by a ribbed section 63 which is notched to maintain the discs 60 at a set distance apart. There is a plurality of ribs 63 running the length of the stack of discs 60.

Figure 24 illustrates the removal means 64 attached along the length of each source 61. The removal means is a series of brush doctors or brushes. The removal means 64 are positioned so they can catch and remove any impinged fibres from the inner edge of the discs 60.

Therefore any impinged fibres will be removed to the inside of the cylinder formed by the

stack of discs 60, but any non-impinged fibres or fines will pass to the outside of the hollow cylinder created by the stack of discs 60.

In operation the fibres are projected from the fibre source 61 towards a plurality of edges 60.

A fraction of the fibres will impinge on the edges 60. The impinged fibres are removed from the edges 60 by the removal mean 64. Two fractions result.

Figures 25 and 26 illustrate graphically the characteristics of different fibre fractions when subjected to the method described herein.

Figures 27 and 28 illustrate the results obtained by employing this method on a specific species, Brown Kraft pinus radiata. Figure 27 illustrates the relationship between length and distribution within the various feed samples. Whereas Figure 28 illustrates the length and distribution percentages for Brown Kraft pinus radiata, fractions resulting after employment of the method described herein.

These are summarised on Figure 29 which illustrates the average lengths and coarseness of the fibres and the accept and reject fractions as compared to those in the raw feed fraction.

VARIATIONS These preferred methods do not preclude other arrangements whereby the fibres can interact with specially prepared surfaces and removed from a flow field or stream to prevent a washing or removing action from the suspension to lessen the effectiveness of the operation.

Other methods could include cylindrical or conical systems with the input stream flowing either inside or outside the elements. Other methods could incorporate either a stationary jet and moving elements, or a moving jet or jets with stationary elements. Any combination of such systems that allow contact with a plurality of solid elements so that the elements, usually smaller in width or thickness than the main dimension of the fibres, would induce momentary adhesion by stapling or impingement, and in essence in accordance to this invention. The subsequent removal of the fibres rapidly from the flowing input stream is important so as to prevent the impacted fibres from being dislodged and removed by the suspension jet following.