Selective Scouring of Dirt from Greasy Wool Part I: A Strategy to Improve Dirt Recovery from Scour Liquor Effluent

Abstract

Laboratory experiments have shown that dirt removal by a cold suint bowl from both low and high yielding Australian merino fleece wools can increase from 10-25% to 40-60% by adding certain surfactants, builders, or their mixtures. Factorial exper iments show that increasing the concentration of the additives has the most significant positive effect on dirt removal and recovery, and grease removal. Increasing the tem perature of the suint bowl from 20 to 35°C has a less significant positive effect on each of the responses. Changing from a wool with high dirt and medium grease (low yielding) to a wool with low dirt and medium grease (high yielding) results in a lower percentage of both dirt and grease removed by the modified suint bowl, but the overall removal of both is greater than when no additives are present. Factorial experiments also show that one very effective formulation comprises a mixture of nonionic sur factant and soda ash. The settling efficiency of dirt (which determines dirt recovery) is determined in both hot and cold scour bowls containing a nonionic surfactant and soda ash. The settling efficiency decreases as the grease concentration and grease to dirt ratio in the liquor increase with continuous scouring. In all cases, dirt recovery from the modified cold suint liquor is greater than from a cold bowl containing no additives. The highest recovery is between 45-50% of the dirt entering on the greasy wool, which is over twice the recovery from a suint bowl without additives. Only a small amount of recoverable grease is removed from the fiber (less than 10% of the total grease present) by the modified suint bowl; the remaining grease removed is nonrecoverable (30-60% of the total grease present).