WO 97/34031 PCT/aU97/00169
BACKWASHING OF PARTIALLY PROCESSED WOOL
.M. .
pfttw Invent"
The present invention relates to the backwashing of partially processed wool and more particularly to an improved method for washing pre-comb v.ool in shver form is Ppcfcgrwnd 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 callcd backwashing and the wool was essentially subjected to a three-step scour Typically, 24 slivers each 20 having a linear density of 30 to 40g/m were fed to a first scouring bowl at u speed of about lOm/min The first scounng bowl normally contained warm water at 35 to 45SC 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 nnse bowl The slivers were then directed to a third bowl which was a warm rinse 25 bowl In some instances the ^livers were then directed to a further rinse bowl. Each of the scounng and nnse bowls was fitted with guide rolls and squeeze rollers to aid in the scounng and rinsing processes After leaving the nnse bowls the slivers passed through a drying machine and then entered a gill box
The object of backwashing was to remove any impunties 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
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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 scounng stage, and thus the relative value of backwashing diminished This factor, coupled with the high cost of backwashing operations, resulted in the practice s 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 shnnkproofing methods
In the last decade or so, the output production rate (te kg/hr) in scounng 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, and until the present invention, the value of backwashing wool slivers for use in modem high speed spinning operations had not been re-evaluated There has been a reluctance to re-introduce backwashing pnmanly 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 a relatively poor running efficiency
As already noted, traditional backwashing practice amounted to a further scounng step It has now been realised, in accordance with the invention, that the carding process modifies the adhesion of scourable residuals in the wool and that traditional backwashing to remove these residuals from carded wool is inefficient because it is unnecessary It has been found that these residuals are located pnmanly on outer surfaces of the wool fibres in sliver, bound quite loosely to the structure, and that they can be dislodged without any need for immersion of the sliver as traditionally practised, and the consequent intensive diying Backwashing can therefore be earned out pnor to combing at much lower cost than before, offering, at an acceptable cost, the possibility of improvements in topmakmg as well as a reduced frequency of roll laps, spinning breaks and winding faults These advantages offer substantial economic benefits to wool spinners Particular benefits may be incurred for superfine wools, and perhaps for wools that are difficult to scour
Any re-introduction of the backwashing concept as an integral part of modem practice rather than as a stand-alone unit must recognise that the present and foreseeable
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IS
DV96066004Q
33165ft delivery speeds of modern carding and gilhng machines are in the order of 60 to 150m/min
The present invention provides, m one aspect, a process for treating a fibre assembly travelling at 60m/min or greater, including -
subjecting the fibre assembly to a scounng treatment effective to remove contaminants apart from residual contaminants from the fibre assembly,
carding the scoured fibre assembly in a manner resulting in the adhesion of said residual contaminants being reduced and the residual contaminants being located pnmanly on the outer surfaces of the fibres m the assembly, and backwashing the fibre assembly subsequent to said carding by directing one or more flows of a fluid to dislodge said residual contaminants from the assembly
The invention also provides, in another aspect, apparatus for treating a fibre assembly travelling at 60m/mm or greater, including -
scounng means for subjecting the fibre assembly to a scounng treatment effective to remove contaminants apart from residual contaminants from the fibre assembly, and means for carding the scoured fibre assembly in a manner resulting in the adhesion of said residual contaminants being reduced and the residual contaminants bemg located pnmanly on the outer surfaces of the fibres in the assembly, and means for backwashing the fibre assembling subsequent to said carding by directing one or more flows of a fluid to dislodge said residual contaminants from the assembly subsequent to said carding
The apparatus may further include means to thereafter subject the fibre assembly to a drying step sufficient to remove a selected proportion of said fluid retained by the fibre assembly after backwashing
Summary of the Invention
3/2
pcT/Au 2 7/00163
RECEIVED 1 4 MAY 1998
In a still further aspect, the invention provides a process for backwashing a fibre assembly travelling at 60m/min or greater, subsequent to carding of the assembly, including passing the fibre assembly through a single bath of a cleaning fluid for a dwell time of 5 seconds or less
The process and apparatus is preferably integrated into wool processing plant, eg worsted processing plant, so that the backwashing is applied to the fabnc assembly on the run between other stages, eg between carding and gilhng
Said drying step may consist of or include directing a jet of air onto the fibre assembly to evaporate or knock away the fluid
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The washed sliver may additionally be rinsed prior to drying
Preferably, control is maintained over the fibres during backwashing so that the fibres of the sliver are not disturbed during the process This may be effected, eg, by s gripping the sliver at spaced locations, at a separation approximately equal to or less than the mean fibre length in the sliver This would typically be a spacing between contacts in the range 40-60mm
The fibre assembly may be pre-wet, eg with a pad, before being subjected to the 10 directed flow(s) of fluid These flows may include an initial jet of liquid and then z rinsing jet of liquid
Preferably, saturation of the fibres cif the assembly is minimised or avoided, eg by confining the residence time in liquid streams to a maximum of a few seconds, eg 1 or 2 15 sees, and the degree of wetness is maintained at a level sufficient for contaminants to be dislodged while minimising the energy necessary to effect the drying step
The inventive method and apparatus may be advantageously applied to a multiple
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sliver feed and more particularly to a 'multiple sliver feed prior to entTy into a gilling 20 machine
The fluid utilised is preferably liquid water, most preferably warmed above ambient, and may include a cleaning medium, but may alternatively be steam, pastes, solvents or foams
The backwashing step is ^preferably incorporated in a high speed carding or ct~nbing operation, eg at a delivery speed in the range 60 to 120m/nun
Advantageously, a force <!g suction is applied to improve the penetration of the 30 washing, rinsing and/or drying fliids among the fibres of the assembly
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WO 9734031 PCT/AU97/00169
Brief Description of the Drawings
Embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings, in which -
Figure 1 is a schematic side view of a first embodiment of the invention, s Figure 2 is a schematic side view of a second embodiment of the invention,
Figure 3 is a schematic side view of a thud embodiment of the invention,
Figure 4 is a schematic side view of a fourth embodiment of the invention,
Figure 5 is a schematic side view of an alternative form of the embodiment shown in Figure 4, and jo Figure 6 is a cross-sectional diagram of a still further embodiment of the invention utilising suction drums in a liquor bath
EmMmrntg of thy ftiyentfon
For simplicity of explanation, the various embodiments of the invention illustrate a is single carded sliver being individually washed However, it should be appreciated that the embodiments could be modifled so as to enable multiple sliver feed, and indeed multiple feed would be the usual practice.
Figure 1 illustrates a sliver 10 being passed successively through the nips 11 of a 20 series of spaced pairs 12 of opposed contra-rotaung rollers 12a, 12b The nips 11 are spaced at a distance R which is preferably less than the mean length of the fibres m the sliver 10 The shver 10 is pie-wet at a pre-wetting station 14, eg a pad, prior to being sprayed by a jet or jets 16 of warm water and a cleaning medium The sliver 10 then passes a jet or jets 18 of rinse water
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Residual contaminants in the sliver have been found to be pnmanly loosely bound at the outer more exposed surfaces of the fibres, having been encouraged to those locations in the carding process In many applications, there is no need to immerse the sliver in the traditional way in r. scouring bowl, and it has proven sufficient in a preferred embodiment 30 to wash away the contaminants with an initial jet of warm cleaning water and a follow up nnse jet Furthermore, because there is no immersion, saturation of the fibres is reduced by an appropriate level of liquid flow The energy required to achieve drying is minimised
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In some cases, a separate on-line drying facility 19 will be necessary, in others no drying operation will be required A jet of air will typically be sufficient
It may be appropriate to cuttle or fold the sliver 10 m the drying facility
Figure 2 illustrates an alternative arrangement to that illustrated in Figure 1, wherein rather than passing through the nips of opposed pairs of rollers 12a, 12b, the sliver 110 traverses about a series of spaced rollers 112a, 112b, 112c The sliver 110 is still pre-wetted, sprayed with jets 116 of warm water and cleaning medium, and then rinsed (112)
Figure 3 illustrates an alternative arrangement which allows the cleaning medium, which typically comprises warm water and detergent, to be forced through the sliver 210 to improve penetration among the fibres It may be necessary to force the cleaning fluid through the sliver 210 because of the physical propertic, of the wool As illustrated in is Figure 3, the sliver 210 would pass through the nips 211 of a series of pairs 212 of opposed rollers 212a, 212b, which adopt a similar arrangement to that shown in Figure I However, at the point where the sliver 210 is sprayed with jets 216 of warm water and cleaning medium, suction 215 would be applied to draw the warm water and cleaning medium now containing the contaminants through the slivers 210 and thus wash all of the fibres in the 20 sliver
Figure 4 illustrates an alternative arrangement to that shown in Figure 3 wherein the wool sliver 310 passes between a guide roll 320 and a suction drum 322, travels across the suction drum 322, and then passes between the suction drum 322 and a second guide roll 25 3 24 As the sliver 310 passes oyer the suction drora 322 a spray of cleaning medium would be applied by the jets 316 onto the sliver 310 Suction would then be applied (315) so as to draw the cleaning medium through the sliver 310 and into the suction drum
Figure 5 illustrates an arrangement wherein two suction drums 422 are combined 30 Multiple suction drums 422 could be used to enable multiple washing stages and/or rinsing stages or to simply enable consecutive washing and rinsing stages Furthermore, additional guide rolls (not shown) may be included in between each of the suction drums
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Figures 2 to 5 do not include drying facilities but these wop'j be provided where necessary as preferred
Although all the embodiments include a pre-wettmg step, this may be not required 5 and is not essential Conversely, in some applications, a more positive pre-wetting step may be needed For example, the sliver may be drawn briefly through a single bath of cleaning fluid for pre-wetting purposes
It may be desirable in some applications for the last or exit nip in the embodiments 10 of Figures 1 and 3 (and possibly the centre mp in Figure 1) to be a pressunzed nip, and for the embodiments of Figures 2, 4 or 5 to mclude one or more pressunzed downstream and/or exit nips These may facilitate optimum downstream fluid content in the sliver
In one embodiment of the invention it is envisaged that the re-washing apparatus is would be designed for re-washing a single sliver as it exits the card or as it feeds to a gilhng machine It is also envisaged that the apparatus may be used to wash 'he sliver feed to a gilhng machine in each of these arrangements it is envisaged that the sliver would be wetted, washed, possibly rinsed and Men dried to an appropriate moisture content so that the shver can then be subsequently processed without delay, le the process is integrated 20 into existing processing plant
In a still further embodiment illustrated in Figure 6, application of cleaning medium is by passage about and under a series of suction drums 522a, 522b,522c through a bath 530 of warm water and cleaning medium The bath is held within a bowl 532 in a 25 configurauon similar to a single station of a traditional multiple bowl scounng or backwashing installation The first suction drum 522a co-acts with a complementary contra-rotating roller 534 to define; a delivery nip 51 la. A pair of exit pressurized nips 51 lb,511c are associated with the final suction dram 522c and adjacent exit rollers 536,537 Effluent is collected at 538 at the intake from roller 534 and excess liquor is 30 collected at 540 from nips 51 lb,51 lc for filtering and recycling
Spray jets 516 of further cleaning medium and warm waur may be applied to the wetted sliver downstream of suction drum 522c It should also be noted that the suction
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drums can be replaced by solid dip rollers or by a single, larger diameter suction drum or solid dip roller without any significant deterioration of the process outcome
The backwashing effected by the embodiment of Figure 6 is quite different from traditional backwashing in that there is only one bowl and that the dwell time in the bath is much less than the conventional dwell time in each of the two to four baths of traditional backwashing, e g preferably 5 sees or less, more preferably less than '/3 of the conventional dwell time This difference arises from the different travel speeds of the sliver, e g 60 m/min or more m the embodiment of Figure 6 compared with 15 to 20 m/min in traditional backwashing practices
The cleaning medium may by simply liquid water or may comprise an aqueous detergent whicn may be mixed with water, steam, cleaning paste, foam, or other appropriate cleaning medium It may be necessary to raise the temperature of the cleaning medium above those typically used to aid the cleaning process
Instead of warm water, steam may be employed as the washing jet
It is envisaged that apparatus and methods according to embodiments of the present invention would provide all of the advantages of prior art backwashing apparatus and methods without substantially delaying the processing time required to prepare the wool ready for spinning Whereas pnor an backwashing apparatus and methods required the slivers to dwell and soak in each of two to four scounng bowls for up to 8 to IS seconds, washing of the sliver in accordancc with embodiments of the present invention would ideally be achieved in I to 2 seconds or less Forced liquid traversed, eg using a vacuum, can improve penetration of the sliver and washing contact with all or most fibres Embodiments of the invention seek to wash contaminants from the surface of the fibres and preferably avoid saturation of the fibres This will reduce both washing and drying times and drying energy Accordingly, embodiments of the present inventicr: arc able to be incorporated into current high speed carding and combing processes (eg up to 120 m/min) without the need to reduce the delivery speed
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It will be appreciated that the process of the invention might be utilised, m certain applications, to control the moisture content of the sliver within a desired range This might be effected by setting the liquid flow and drying parameters, relative to sliver dehveiy speed, to produce a selected moisture contenL The process may also be s additionally used for traditional backwashing purposes, eg for nnsing after dyeing or as a preparation for applying resins to wool in some shnnkproofing methods
Embodiments of the invention have been described by way of example only and modifications are possible within the scope of the invention
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It will also be understood that where the term "comprises" or its grammatical variants is employed herein, it is equivalent to the term "includes" and is not to be taken as excluding the presence of other elements or features
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