Cotton foreign matter

OTTON DUST IN THE WORKPLACE is a major problem facing the cotton and textile industry. Workers breathing cotton dust may develop byssino-sis, a disease that resembles chronic bronchitis and, in its later stages, emphysema. The agent believed to cause the disease is not actually cotton but microscopic foreign matter in the cotton that is released when bales are processed in the mills. 

Morey, Sasser, Bethea, and Kopetzky ( ) examined and classified the plant parts in Shirley analyzer waste from six raw cottons that had been processed through the model card room at North Carolina State University. Bract, leaf, weeds, veins and endocarp were the major plant parts present. Bract and leaf constituted up to 52 percent of the foreign matter in the cottons they examined. There was evidence that using gin lint cleaners reduced the total trash content but Increased the proportion of bract relative to other foreign-matter particles remaining in the fiber. 

Foreign-matter Percentage in Three Grades of Cotton... 

Durrenberger (10, 11) in 1973 studied airborne particulates at varying distances from gins in Texas. He developed a prediction equation for estimating the dust concentration in air downwind from gins. The equation was based on ginning rate, foreign matter content of the cotton as harvested, and took into account the amount of emission control equipment in use at the gin. His study showed that the heavier particulates released into the atmosphere fell to earth near the gin but that the finer particles were transported several hundred meters. 

Accumulated evidence shows that in cotton mills, byssinosis is not caused by.the cotton lint itself, but rather by foreign matter in the dust arising from the processing of raw fibers (12). 

After harvesting, the seed cotton (consisting of cotton fiber attached to cottonseed and plant foreign matter), a raw perishable commodity, is transported to the ginning plant in trailers or modules, or is stored in the field in modules. In the United States, module storage is used for almost the entire crop. Field storage in modules maximizes efficiency at the gin. 

Large leaf is usually less objectionable because large particles are more easily removed by the textile manufacturing process. Leaf and other foreign matter in cotton must be removed... 

Strippers are efficient and can harvest up to 99% of the cotton from the plant. They are nonselective and remove not only the seed cotton but also the cracked and unopened bolls, the burs, and other foreign matter. The extra foreign matter requires additional cleaning at the gin. 

Figure 3.2 schematically depicts a typical spinning preparation line (blow room) for cotton. It starts on the left with a bale breaker, followed by several cleaning units and a mixer, and is completed with a dust and foreign matter extractor. The next step is carding (not shown). 

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