Removal of plastic sheet material with normal cotton ginning equipment

Authors: Byler, Richard; Boykin Jr, James; Hardin Iv, Robert

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 2/15/2013
Publication Date: 6/1/2013
Citation: Byler, R.K., Boykin Jr, J.C., and R.G. Hardin IV. Removal of plastic sheet material with normal cotton ginning equipment. Proceedings of Beltwide Cotton Prod. Res. Conf., National Cotton Council, San Antonio, TX, pp 676-685, CD ROM. 2013.

Interpretive Summary: Cotton produced in the US is known to be relatively free of contaminants. Recently very low but increasing levels of plastic sheet material have been noticed in cotton bales from the US. Plastic material is commonly found in the cotton growing areas including agricultural mulch, shopping bags discarded by customers, irrigation tubing, and more recently seed cotton module wrap. If the plastic material becomes entrained in the seed cotton entering the gin presumably much of it will be removed when it passes through the normal cleaning equipment. However, no references were found regarding the removal of sheet-type plastic material by normal ginning equipment. In this study pieces of varying predetermined sizes of sheet-type plastic materials commonly found in cotton growing areas were intentionally mixed with seed cotton and introduced into a research cotton gin. All outputs of the ginning system were monitored for the plastic material. It was found that the equipment generally does not as effectively remove lighter weight and larger plastic pieces compared to smaller and heavier material. Overall 17% of the material intentionally mixed into the seed cotton entering the ginning equipment was subsequently found to be mixed with the lint. Some of the plastic was shredded by the ginning equipment and some of it passed through to the lint virtually unchanged. The most important message from the study was that ginners and producers need to be vigilant in keeping plastic materials from becoming mixed with the seed cotton because the normal cotton cleaning equipment is not effective enough in removing the plastic which then becomes a contaminant in the US cotton.

Technical Abstract: US cotton is known to be relatively free of contamination but occasionally pieces of sheet plastic are found in cotton bales produced in the US. To better understand how ginning equipment handles pieces of sheet plastic 5 types of plastic commonly found in US seed cotton fields or used in handling seed cotton were cut into several different sized pieces and added to seed cotton. This mixture was processed in a research ginning system with normal ginning equipment sequence and all outputs from the system were examined for plastic materials. Overall the cylinder-type cleaners removed 10% of the material, the extractor-type cleaners removed 56% of the material, and 17% was retrieved from the lint. Plastic pieces of larger area or that were thinner were more likely to contaminate the lint. Gin managers need to be aware that contamination by sheet plastic is an issue and inform producers and gin employees that they need to be vigilant in not allowing plastic to enter the gin because gin cleaning machinery does not remove all of the contamination.