BACKWASHING OR PARTIALLY-PROCESSED WOOL

Abstract: Apparatus for treating a travelling fibre assembly, e.g. subsequent to scouring and carding of the assembly, or subsequent to combing of the assembly, includes means for retaining a shallow flowing liquid bath; and means to guide the fibre assembly through the bath whereby the shallow flowing liquid is effective to dislodge and/or rince away residual contaminants from the fibre assembly while reducing drag on the fibre assembly and so minimising the incidence of breaks in the fibre assembly.

Description: BACKWASHING OR PARTIALLY-PROCESSED WOOL Field of the Invention The present invention relates to the backwashing of partially processed wool and more particularly to an improved method for washing pre-comb or post-comb wool in sliver form. Background Art Prior to the 1960's it was established practice in many wool combing plants to wash wools downstream of carding. Some combers re-washed after carding while others preferred to defer the process until after combing. This process was called backwashing and the wool was essentially subjected to a three-step scour. Typically, 24 slivers each having a linear density of 30 to 40g/m were fed to a first scouring bowl at a speed of about lOm/min. The first scouring bowl normally contained warm water at 35 to 45°C and approximately 0.5% detergent. The slivers were then sent to a second bowl which either contained warm water and detergent in the same manner as the first bowl or acted as a warm rinse bowl. The slivers were then directed to a third bowl which was a warm rinse bowl. In some instances the slivers were then directed to a further rinse bowl. Each of the scouring and rinse bowls was fitted with guide rolls and squeeze rolls to aid in the scouring and rinsing processes. After leaving the rinse bowls the slivers passed through a drying machine and then entered a gill box. The object of backwashing was to remove any impurities still remaining after scouring and carding, thereby improving the colour and hence the commercial value of the top. Other subsidiary advantages of backwashing were small improvements in the yield and average fibre length of the top. During the 1960's wool scourers adopted the use of synthetic detergents rather than the traditional soap. Synthetic detergents were found to be much more efficient in cleaning wool at the initial scouring stage, and thus the relative value of backwashing diminished. This factor, coupled with the high cost of backwashing operations, resulted in the practice of backwashing being largely abandoned. Backwashing however remained in use for rinsing after dyeing, and as a preparation for applying resins to wool in some sliver shrinkproofing methods. In the last decade or so, the output production rate (i.e. kg/hr) in scouring operations has increased. As a consequence of this increase there has been an increase in the level of scourable residuals residing in commercial consignments of scoured wool. Irrespective of this trend, the value of backwashing wool slivers for use in modern high speed spinning operations was not re-evaluated until relatively recently. There has been a reluctance to re- introduce backwashing primarily because of its relatively high cost. Conventional backwashing machines have a high capital cost, require a large operational area, are labour intensive, have a high energy demand and involve a relatively poor running efficiency. As already noted, traditional backwashing practice amounted to a further scouring step. Our co-pending international patent publication WO97/34031 discloses the realisation that the carding process modifies and indeed reduces the adhesion of residual contaminants in the wool and that traditional backwashing to remove these residuals from carded wool is inefficient. It was found that these residual contaminants are located primarily on outer surfaces of the wool fibres in sliver, bound quite loosely to the structure, and that they could be dislodged in a modified lower cost backwashing operation which could avoid the need for intensive drying. Alternative approaches disclosed in international patent publication WO97/34031 include the use of directed flows or jets of cleaning fluid transverse to the sliver, traversal of suction devices, and rapid treatment by brief immersion in a single bath. Any re-introduction of the backwashing concept as an integral part of modern practice rather than as a stand-alone unit must recognise that the present and foreseeable delivery speeds of modern carding machines and feed speeds to gilling machines are in the order of 1 to 2.5 m/sec, compared with 0.4 to 0.5 m/sec in older practice. While the Any re-introduction of the backwashing concept as an integral part of modern practice rather than as a stand-alone unit must recognise that the present and foreseeable delivery speeds of modern carding machines and feed speeds to gilling machines are in the order of 1 to 2.5 m/sec, compared with 0.4 to 0.5 m/sec in older practice. While the approaches proposed in the aforementioned international patent application functioned well at sliver speeds up to about 0.5 m/sec, when they were trialed at speeds of the order of 1 m/sec, difficulties were encountered in achieving adequate removal of residual contaminants. Initial efforts to overcome these difficulties involved reverting to immersion in successive cleaning and rinsing baths, albeit at higher speed (1 m/sec or higher) than in traditional backwashing practice. This improves contaminant removal but incurs an unacceptable level of sliver end breaks. The present invention is directed at least in part to the alleviation of these problems. Summary of the Invention In one aspect of the invention, a process for treating a travelling fibre assembly includes subjecting the fibre assembly to a scouring treatment effective to remove contaminants apart from residual contaminants from the fibre assembly, and carding the scoured fibre assembly in a manner resulting in the adhesion of the residual contaminants being reduced and the residual contaminants being located primarily on the outer surface of the fibres in the assembly. The carded fibre assembly is backwashed eg. subsequent to carding or combing by passing it through one or more liquid baths, at least one of which is a shallow flowing bath effective to dislodge and/or rinse away the residual contaminants from the fibre assembly while reducing drag on the fibre assembly and so minimising the incidence of breaks in the fibre assembly. In another aspect of the invention, apparatus for treating a travelling fibre assembly, eg. subsequent to scouring and carding of the assembly or subsequent to combing of the assembly, includes means for retaining a shallow flowing liquid bath, and means to guide the fibre assembly through the bath whereby the shallow flowing liquid is effective to dislodge and/or rinse away residual contaminants from the fibre assembly while reducing drag on the fibre assembly and so minimising the incidence of breaks in the fibre assembly. The means for retaining a shallow flowing bath preferably includes at least one tray means supported at an inclination so that the shallow liquid bath flows by gravity. The tray means advantageously includes an elongated channel that guides and confines both the fibre assembly and the flow. This channel preferably has, at a downstream location, a nip or other restriction for condensing the fibre assembly. The backwashing may be effected in one embodiment immediately downstream of carding and before gilling. In another embodiment the sliver may be treated post- combing, eg. as top sliver. The inventive process and apparatus may be useful for backwashing or afterwashing top dyed sliver. In one application, the apparatus is located in a fibre processing plant, e.g. a worsted wool processing plant or topmaking plant, downstream of scouring means for subjecting a fibre assembly to a scouring treatment effective to remove contaminants apart from residual contaminants from the fibre assembly, and carding means for carding the scoured fibre assembly in a manner resulting in the adhesion of the residual contaminants being reduced and said residual contaminants being located primarily on the outer surfaces of the fibres in the assembly and thereby disposed to be dislodged and/or rinsed away by the apparatus of the invention. Preferably, the direction of travel of the fibre assembly in the bath is parallel or counter-parallel to the direction of the liquid flow. Means is preferably provided for spraying the liquid of the shallow flowing bath into the bath; this means advantageously includes nozzles arranged to direct at least a portion of the liquid generally down the tray where the fibre assembly enters said shallow bath, whereby to facilitate smooth travel of the fibre assembly. The fibre assembly is preferably supported as it travels through the shallow flowing bath. Where the shallow flowing bath is provided in a tray, this support for the fibre assembly conveniently comprises a fluid layer formed by the shallow bath on the floor of the tray effective to at least in part buoy up the travelling fibre assembly. Preferably, means such as one or more wetting rolls are provided to engage the fibre assembly as it traverses the tray means for removing residual air pockets and thereby promoting enhanced wetting of the fibres in the assembly. A squeezing nip, eg. between contrarotating rolls, is advantageously provided adjacent or downstream of the exit end of the shallow flowing bath. Such a nip may improve the efficiency and reliability of contaminant removal. In a preferred arrangement, the backwashing is effected by passing the fibre assembly through at least two liquid baths. These baths may include a first bath of a cleaning or scouring agent and a second bath of a rinsing liquid, e.g. water. In one arrangement, one of these baths is a static immersion bath and the other is a shallow flowing bath according to the invention. In the case of the static immersion bath, and especially where the travelling speed of the fibre assembly is greater than about 0.5 m/sec, means is preferably provided in the immersion bath to support the fibre assembly, most preferably in a downstream portion of its path of travel through the bath. In an embodiment, both of the liquid baths comprise a respective shallow flowing bath and in a particularly convenient arrangement, these are provided by a pair of inclined trays in a tandem arrangement. In one such arrangement, the fibre assembly substantially reverses its general direction of travel between respective baths: this allows a compact, space-saving layout. The apparatus may further include means to subject the backwashed fibre assembly to a drying step sufficient to remove a selected proportion of the liquid retained by the fibre assembly. The drying step may consist of or include directing a jet of air onto the fibre assembly to evaporate or knock away the liquid. Means may be included in a downstream (with respect to sliver travel) zone of the shallow flowing bath for laterally spreading the sliver to assist with subsequent drying. The process and apparatus may be integrated in wool processing plant, e.g. a topmaking plant or worsted processing plant, so that the backwashing is applied to the fibre assembly on the run between other stages, e.g. between carding and gilling or post combing and gilling when the sliver is top sliver. The fibre assembly may be pre-wet, e.g. with a pad or roller nip, before being passed through the liquid bath. Preferably, saturation of the fibres of the assembly is minimised or avoided, e.g. by confining the residence time in the liquid bath to a maximum of a few seconds, e.g. 1 or 2 seconds and preferably less than 5 seconds, and the degree of wetness is maintained at a level sufficient for residual contaminants to be dislodged and/or rinsed off while minimising the energy necessary to effect the drying step. The inventive method and apparatus may be advantageously applied to multiple fibre assemblies being guided through a common shallow flowing bath or respective such baths. The liquid utilised is preferably liquid water, most preferably warmed above ambient, and may include a cleaning medium. Chemical treatments may also be applied, and the liquid may be a solvent for a reagent or a reagent itself. The backwashing step is preferably incorporated in a high speed carding or combing operation, for example at a delivery speed in the range 1 to 2.5 m/sec. Brief Description of the Drawings The invention will now be further described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic/isometric view of backwashing apparatus in accordance with a first embodiment of the invention, with overhead liquid delivery arrangements omitted for clarity; Figure 2 is a fragmentary isometric view of a condenser tray; Figure 3 is a side view of a condenser tray, showing the liquid delivery facilities; Figure 4 is a cross-section on the line 4-4 in Figure 3; Figure 5 is a schematic side view of backwashing apparatus according to a second embodiment of the invention; and Figure 6 is a block diagram indicating how the backwashing apparatus of Figure 1 or 2 would be fitted into wool topmaking plant. For simplicity of explanation, the embodiments of the invention illustrate a single carded sliver being individually washed. However, it should be appreciated that the embodiments could be modified so as to enable multiple sliver feed. Preferred Embodiments The backwashing apparatus 10 illustrated in Figure 1 includes a tandem pair of oppositely inclined tray units 12,14 with respective sets of input and output rollers 16,17 and 18,19. Tray unit 12 is positioned above tray unit 14 for enhanced compactness and optimum use of space, and the arrangement is such that a travelling sliver (depicted by broken line 5 in Figure 3) is fed in by rollers 16, and guided down the upper tray unit, then reverses its general direction of travel through nipping rollers 17 and about guide roller 18. The sliver is then guided down the lower tray unit to exit the configuration through rollers 19 and an exit squeeze roll pair 84, at a lower level and in the opposite direction to that of entry. Each of the trays has a broad and generally flat outer tray 20a, 20b, with side lips 13 to laterally define the liquid zone, an inner narrower condenser tray 22a, 22b along which the sliver travels, and a perforated liquid spray bar 30 (Figure 3). Each tray unit 12 also has an array of liquid jets 32 for directing liquid onto the upper entrance end of the respective condenser tray 22a, 22b. The liquid directed onto the upper tray unit 12, from both spray bar 30 and jets 32, is water containing a detergent such as a conventional scouring detergent e.g. in a 0.5% concentration, while the liquid directed onto the lower tray unit is simply water so that the lower tray provides a shallow flowing rinsing bath. The general direction of liquid flow in both trays is parallel to the direction of sliver travel. Inner condenser tray 22a is shown in greater detail in Figures 2 to 4. It essentially consists of a substantially semi-circular channel 23, flattened out at its top end to form a broader landing plate 24 onto which the sliver is introduced and onto which jets 32 are directed. Channel 23 is actually slightly greater than 180° in angular extent. At its lower end, channel 23 is closed over and tapers into a funnel 25 with an exit port 26 for sliver 5 at its tip. The cross-sectional shape of channel 23 serves to guide and confine both the sliver 5 and the flow of liquid. Funnel 25 acts as a nip or restriction that condenses the sliver as it emerges from tray 22a directly into the nip of roller set 17, 19. The flow onto trays 22a, 22b has two sources. Firstly, jets 32, fed by transverse manifold tube 33 adjacent to the end of plate 24 and in front of inlet roller pair 16, direct a portion of the liquid generally down tray 22a, 22b (including plate 24) where the sliver enters the resultant liquid bath. This facilitates smooth travel of the slivers, and counters fibre bunching or buckling that might otherwise occur at this point. Secondly, perforated spray bar 30 emits an overhead shower or spray 55 of the liquid to a point about midway down tray 22a, 22b. It will be seen that spray bar 30 is inclined less than the tray, and so shower or spray 55 is increasingly more dispersed down the tray. This liquid forms a shallow downwardly flowing bath through which the sliver passes parallel to the flow. It will be appreciated that the travelling sliver is substantially supported by the floor of the respective trays, although the sliver may not be resting heavily on the floor but is believed to be partly buoyed up by the fluid layer formed by the shallow flowing liquid on the floor of the tray. The shallow flowing baths in trays 22a, 22b are believed to thereby serve a valuable role in supporting and lubricating the sliver in a manner that minimises fibre leakage, or keeps end breaks at an acceptable level, even at high sliver speeds in the region of 1 to 2.5m/sec, thus at least in part alleviating the difficulties met at higher delivery speeds as discussed earlier. The characteristics of the shallow flows in condenser trays 22a, 22b, including the depth, are controlled by respective arrays of drain holes 35, 36; 38 in the trays for outflow of liquid into outer trays 20a, 20b. A first of these arrays comprises lines of drain holes 35, 36 in the floor and sides of trays 22a, 22b in the centre region of the trays. Holes 36 are just below the rims of the channels 23. The other array comprises multiple holes 38 in funnel 25. It will be understood that, for each tray the number and size of these draining holes 35, 36, 38 can be set, in conjunction with the liquid delivery rates from spray bar 30, and jets 32, to prevent excessive back up or overflow of the liquid in the channels, and to manage the flow and depth of the baths at a desired level. Upper tray unit 12 includes a rotatable wetting roller 40, typically of stainless steel, near the upper end of the tray which engages the travelling sliver from above. This wetting roll is not simply a guide roll as in traditional backwashing, but acts to complete the wetting out by ensuring the removal of residual air pockets and thereby promoting enhanced or quicker wetting of the fibres in the sliver. The liquids, including entrained contaminants dislodged from the sliver fibres, overflow from the respective lower ends of the tray units 12, 14 to respective collection tanks 70, 72, preferably for reprocessing and recycling. An overflow collection reservoir for the upper tray is indicated at 74, while liquid from the lower tray unit falls straight into tank 72. The tanks 70, 72 are fitted with electrical heating devices 78, filtration systems (not shown), and pumps 79 for returning the liquid to spray bars 30 and jets 32. Roller sets 16, 17, 19 are configured as squeeze rollers. For roller sets 17, 19, respective underlying lipped splash trays 76, 77 collect the liquid for delivery to collection reservoir 74 and tank 72 respectively. It will be appreciated that the various adjustable parameters of the illustrated embodiment must be mutually set to achieve the optimum result. These parameters include the incline of the trays, sliver speed, the volume rate of flow of the liquid, and the flow characteristics in trays 20a, 20b all of which co-operate to determine the bath contact time for each fibre. An incline in the range 1 in 8 to 45°, preferably greater than in 4, e.g. about 1 in 2, is thought to be suitable and a tray length in the vicinity of 0.8 to 1.2 metres may be satisfactory. It is thought that the rinsing tray unit 14 should be a little shorter than the cleaning liquid tray unit 12, as is reflected in the illustrated embodiment. It is believed that the arrangement illustrated in Figure 1 achieves a satisfactory dislodgment and rinsing away of contaminants for sliver travelling at a speed of the order of 1 to 2.5 m/sec. The contaminants are of course the residual contaminants left after scouring, and carding, now known to be located primarily on outer surfaces of the sliver fibres, bound, quite loosely to the structure. An adequate residence time in each shallow flowing bath is of the order of 1 second or less. The contaminants are carried away in the liquid flow for subsequent separation and disposal. It is thought that contributing elements to the successful outcome, and therefore preferred aspects of the apparatus or method, include the downward shallow flowing liquid, the overhead spray, the jets 32, the squeezing action of the roller sets 16, 17 and 19, wetting roller 40, the confining of the flow and the sliver by the form of inner tray 22a, 22b, and the condenser funnel 25. The illustrated backwashing apparatus may be integrated in wool processing plant, e.g. a topmaking or worsted processing plant, so that the backwashing is applied to the fibre assembly on the run between other stages, typically between carding and gilling. This is schematically depicted in Figure 6, where the scouring stage 90, card 92, backwashing apparatus 10 and gilling stage 94 are shown in series for processing sliver 5. In the scouring stage 90, uncleaned greasy wool is subjected to a scouring treatment, typically with several baths, effective to remove contaminants apart from residual contaminants from the fibrous mass. This is delivered to the card 92, where, as is now understood the carding treatment results in the adhesion of the residual contaminants being reduced and these residual contaminants being located primarily on the outer surfaces of the fibres in the fibre assembly, and thereby disposed to be dislodged and/or rinsed away when the fibre assembly is delivered as sliver to backwashing apparatus 10. The backwashed sliver will usually be dried (not shown), and is passed to the gilling stage 94. In an alternative application, the illustrated apparatus may be used post combing, and indeed to sliver may be top sliver. In one such application, the apparatus may be employed to backwash or afterwash top dyed sliver. An alternative embodiment 10' is depicted in Figure 5, and differs from that of Figure 1 in a number of respects. A shallow flow is only employed for the rinsing stage, which has an inclined tray unit 14' with input and output roller pairs 18', 19', and spaced spray nozzles 20'. Moreover, the cleaning stage is a more conventional scouring bowl 12' in which the sliver is fully immersed in a substantially static slowly replenished bath of cleaning liquid. The arrangement of tray unit 14' differs from that of tray unit 14 in Figure 1 in that the sliver travels up the inner tray, i.e. oppositely to the flow. The scouring bowl 12' differs from conventional scouring bowls in that the input roller pair 16' supports cleaning/scouring liquid 16a above its nip for pre- wetting purposes, and in that the exit run 6 of the sliver is supported within the bath by the upper inclined run of a travelling roller-mounted continuous belt 78. This assists in reducing end breaks in the bowl bath at high sliver speeds. Immersion time in the scouring bowl can be adjusted with a vertically moveable immersion roller mechanism 80, and the rinsing stage is underlaid by a splash collection tray 82. It will be noted that both embodiments include a squeeze roll pair 84 downstream of the rinsing stage for minimising or adjusting the moisture content of the sliver delivered by the backwashing apparatus. This assists in achieving more efficient and uniform drying in a downstream drying stage. The upper roller advantageously has a layer for adjusting and effecting greater uniformity of liquid distribution in the sliver, and may be a "Nollap" roll; the lower roll is then preferably polyurethane-coated stainless steel. In an alternative arrangement, squeezer roll pair 84, or the set of exit rollers and squeeze rolls 84, is substituted by a tongue-in-groove roller pair. This style of output rollers is thought to be useful in concentrating the pressure of the top roller on the fibre assembly, rendering this pressure more uniform at the nip, reducing the level of regain or moisture content, and achieving more even moisture distribution. The load on the subsequent dryer can thereby be reduced. Drying may also be aided by providing, just inside the exit end of tray unit 14, 14 in a downstream zone of the shallow flowing bath in the inner tray, a device foi ¬ laterally spreading the sliver. Such spreading is found to be especially facilitated by effecting the spreading while the sliver is still within the shallow flowing liquid in the tray. It is emphasised that, while the illustrated embodiments show tray units with inner and outer trays, each tray unit may be a single tray structure.

Claims: Claims 1. Apparatus for treating a travelling fibre assembly, eg. subsequent to scouring and carding of the assembly, or subsequent to combing of the assembly, including: means for retaining a shallow flowing liquid bath; and means to guide the fibre assembly through the bath whereby the shallow flowing liquid is effective to dislodge and/or rinse away residual contaminants from the fibre assembly while reducing drag on the fibre assembly and so minimising the incidence of breaks in the fibre assembly. 2. Apparatus according to claim 1 wherein said means for retaining a shallow flowing liquid bath includes at least one tray means supported at an inclination so that the shallow liquid bath flows by gravity. 3. Apparatus according to claim 2 wherein said tray means includes an elongated channel that guides and confines both said fibre assembly and said flow. 4. Apparatus according to claim 2 wherein said elongated channel comprises an inner tray and said tray means further includes an inclined outer tray on or above which said inner tray is disposed. 5. Apparatus according to claim 3 or 4 wherein said channel includes, at a downstream location, a nip or other restriction for condensing said fibre assembly. 6. Apparatus according to claim 3, 4 or 5 wherein said channel includes arrays of drain holes for outflow of said liquid, arranged for controlling the characteristics including depth of said shallow flow. 7. Apparatus according to any preceding claim, further including means for spraying the liquid of the shallow flowing bath into the bath. 8. Apparatus according to claim 7, wherein said spraying includes nozzles arranged to direct at least a portion of the liquid generally down the tray where fibre assembly enters said shallow bath, whereby to facilitate smooth travel of the fibre assembly. 9. Apparatus according to claim 7 or 8, wherein said spray means includes an arrangement for directing multiple streams of the liquid downwardly onto the tray means and fibre assembly thereon over at least a longitudinal portion thereof. 10. Apparatus according to any preceding claim 1 further including wetting means to engage the fibre assembly as it traverses said tray means for removing residual air pockets and thereby promoting enhanced wetting of the fibres in the assembly. 11. Apparatus according to any preceding claim, further including a squeezing nip adjacent or downstream of the exit end of the shallow flowing bath. 12. Apparatus according to any preceding claim wherein said means for retaining a shallow flowing liquid bath includes a pair of said tray means arranged for providing respective separate shallow flowing baths, each supported at an inclination so that the respective baths flow by gravity, and arranged mutually in tandem and with said guide means so that the travelling fibre assembly traverses one bath then the other. 13. Apparatus according to claim 12 further including means for providing different liquids for the respective baths so that, in use, one bath may include a cleaning or scouring agent, while the other serves as a rinsing bath. 14. Apparatus according to claim 12 or 13 wherein said tray means are arranged one generally above the other so that the fibre assembly substantially reverses its general direction of travel between the respective baths. 15. Apparatus according to any one of claims 1 to 11, further including means for providing a static immersion bath, said guide means being arranged to guide the fibre assembly through the bath of the shallow flowing liquid and the static immersion bath. 16. Apparatus according to any preceding claim, further including means to subject the backwashed fibre assembly to a drying step sufficient to remove a selected proportion of the liquid retained by the fibre assembly. 17. Apparatus according to any preceding claim, located in a fibre processing plant downstream of scouring means for subjecting a fibre assembly to a scouring treatment effective to remove contaminants apart from residual contaminants from the fibre assembly, and carding means for carding the scoured fibre assembly in a manner resulting in the adhesion of said residual contaminants being reduced and the residual contaminants being located primarily on the outer surfaces of the fibres in the assembly and thereby disposed to be dislodged and/or rinsed away by said apparatus. assembly, and carding means for carding the scoured fibre assembly in a manner resulting in the adhesion of said residual contaminants being reduced and the residual contaminants being located primarily on the outer surfaces of the fibres in the assembly and thereby disposed to be dislodged and/or rinsed away by said apparatus. 18. Apparatus according to claim 17 arranged so that the direction of travel of the fibre assembly in said bath is parallel or counter-parallel to the direction of the liquid flow. 19. Apparatus according to any preceding claim arranged for guiding multiple fibre assemblies though a common said shallow flowing bath or respective such baths. 20. A method of treating a travelling fibre assembly, including: subjecting the fibre assembly to scouring treatment effective to remove contaminants apart from residual contaminants from the fibre assembly; carding the scouring fibre assembly in a manner resulting in the adhesion of said residual contaminants being reduced and the residual contaminants being located primarily on the outer surfaces of the fibres in the assembly; backwashing the fibre assembly, eg. subsequent to said carding or combing, by passing it through one or more liquid baths; wherein at least one of said liquid baths is a shallow flowing bath effective to dislodge and/or rinse away said residual contaminants from the fibre assembly while reducing drag on the fibre assembly and so minimising the incidence of breaks in the fibre assembly. 21. A method according to claim 20 further including providing said shallow flowing bath in an elongated channel that guides and confines both said fibre assembly and said flow. 22. A method according to claim 20 or 21 further including condensing said fibre assembly at a nip or other restriction at a downstream location. 23. A method according to claim 20, 21 or 22, further including spraying the liquid of the shallow flowing bath into the bath. 24. A method according to claim 23 wherein at least a portion of the liquid is directed generally down the tray where the fibre assembly enters said shallow bath, whereby to facilitate smooth travel of the fibre assembly. 25. A method according to any one of claims 20 to 24 further including squeezing the fibre assembly in a squeezing nip adjacent or downstream of the exit end of the shallow flowing bath. 26. A method according to any one of claims 20 to 25 including passing the fibre assembly through at least two separate shallow flowing baths. 27. A method according to claim 26 wherein different liquids are provided for the respective baths, so that one bath includes a cleaning or scouring agent and the other serves as a rinsing bath. 28. A method according to any one of claims 20 to 27 wherein the direction of travel of the fibre assembly in said bath is parallel or counter-parallel to the direction of the liquid flow. 29. A method according to any one of claims 20 to 28 wherein the fibre assembly is supported as it travels through the shallow flowing bath. 30. A method according to claim 29, wherein said support includes a fluid layer formed by the shallow bath on the floor of a tray means effective to at least in part buoy up the travelling fibre assembly. 31. A method according to any one of claims 20 to 30, integrated in a wool processing method so that the backwashing is applied to the fibre assembly on the run between other stages, e.g. between carding and gilling or post combing. 32. A method according to any one of claims 20 to 31 further including pre-wetting the fibre assembly, before it is passed through the liquid bath. 33. A method according to any one of claim 20 to 32 wherein the residence time in the liquid bath is less than 5 seconds. 34. A method according to any one of claims 20 to 33 wherein the fibre assembly is delivered at a speed in the range 1 to 2.5m/sec.

Inventors: AHERN MICHAEL JOHN, ROBINSON GARY ALFRED, SKOURTIS CHRISTOS, AHERN, MICHAEL, JOHN, ROBINSON, GARY, ALFRED, SKOURTIS, CHRISTOS
Applicants: AHERN MICHAEL JOHN, COMMW SCIENT IND RES ORG, ROBINSON GARY ALFRED, SKOURTIS CHRISTOS, AHERN, MICHAEL, JOHN, COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH ORGANISATION, ROBINSON, GARY, ALFRED, SKOURTIS, CHRISTOS
Application year: 1998
Main classification: D01B3
IPC codes: D01B3