Australian Wool Textile Research (continued)

This then at that time was recognized as the major problem in commercial scouring -how to produce scoured wool, as clean as possible, with the minimum of fibre entanglement, yet maintain a maximum throughput.

Efforts had already been made in Australian industry to develop methods of scouring wool using organic solvents. One of these techniques was taken over by CSIRO, and developed to the commercial stage.[14] This system was also simple. Instead of moving through bowls, wool was moved by a travelling conveyor under jets of organic solvent (white spirit). There were two stages of jetting with solvent, followed by two stages of jetting with water. The water jets displaced the solvent from the wool, and dissolved the residual suint (perspiration salts), which was insoluble in white spirit. The sludge from the first bowl was run through a centrifuge, separating the solvent from the grease, allowing the solvent to be re-used. This scouring system gave less disturbance of the wool, resulting in lower entanglement. Comparative trials showed that about one-fifth less noil (waste in topmaking) came from solvent-scoured wool as compared with wool scoured conventionally.

The process was eventually adopted by G. H. Michell and Sons in Adelaide. The capital cost for such a plant and the potential of fire (solvent vapour was not recovered), however, proved a major deterrence to more widespread adoption, and attention turned towards the development of a gentler action, aqueous scouring machine. This eventually spawned in the early 1960s the aqueous jet scour[15] (Fig. 14) in which again the wool was transported under jets of liquor -this time water containing selected, newly introduced non-ionic detergents -by a conveyor and perforated-drum arrangement (Fig. 15). Several commercial installations of this development were made throughout the world by Wessberg & Tulander, a Sydney company, and many of the principles aimed at achieving reduced fibre entanglement were incorporated by other manufacturers in scouring machines of more traditional design.

14 The CSIRO jet scour. Instead of immersing the greasy wool in a large volume of scour liquor, in the CSIRO jet the wool is passed under a series of jets of liquor. Less entanglement of fibres results.

15 Diagram of CSIRO jet scour. See Figure 14.

On the woollen system of processing, scouring is followed by carbonising (Fig. 16) to remove seed and burr. In the early 1950s the local industry was using very drastic conditions of treatment with sulphuric acid to remove the vegetable matter, resulting in considerable fibre damage. In 1952, the Biochemistry Unit in Melbourne set out to improve this situation, and the research resulted in a practical method for reducing acid damage to the wool which was widely applied in industry, firstly in Australia and then overseas. The method[16] made use of detergents which reduced the penetration of acid into the wool, but had no effect on acid absorption by the vegetable.

16 The carbonizing process entails treatment of vegetable-containing wool with dilute sulphuric acid, drying and then baking. During the baking, the concentrated acid degrades the vegetable matter, which is then crushed to fragment it in a crusher similar to that shown above.

Australian Academy of Technological Sciences and Engineering