Performance of a cotton gin machine that removes plastic contamination from seed cotton

Authors: Whitelock, Derek; Armijo, Carlos; FUNK, PAUL; KOTHARI, NEHA - COTTON, INC.; MARTIN, VIKKI - COTTON, INC.

Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2022
Publication Date: 11/18/2022
Citation: Whitelock, D.P., Armijo, C.B., Funk, P.A., Kothari, N., Martin, V. 2022. Performance of a cotton gin machine that removes plastic contamination from seed cotton. Journal of Cotton Science. 26(2):76-84. https://doi.org/10.56454/VKNF3731.
DOI: https://doi.org/10.56454/VKNF3731

Interpretive Summary: Plastic contamination is the most pressing issue for the U.S. cotton industry today. Due to this problem, U.S. cotton has lost the 7 cents per pound premium it brought on international cotton markets. Plastic contaminants are often introduced prior to ginning, but cotton gin machinery can tear and shred the plastics so that they become more difficult to remove. The best solution is to keep plastic out of the cotton altogether but, when it does slip in, methods to remove the plastics at the gin are needed. A cotton gin machine developed and used to combat the plastic contamination problem in Chinese cotton was tested to compare its performance at removing typical plastics found in U.S. cotton to that of conventional cotton gin seed cotton cleaners. The results showed that the contamination cleaner was more effective at removing plastic contamination than the seed cotton cleaners. Lighter and more flexible shopping bag material was removed better than heavier and stiffer round module wrap. Smaller size pieces were more effectively removed from seed cotton than larger pieces. Increasing air flow to the contamination cleaner improved plastic removal, but seed cotton captured with the plastic also increased. For cotton ginneries, capturing plastic pieces will need to be balanced with also removing seed cotton with the plastics. This contamination cleaner may be an off-the-shelf tool for some ginneries to use in the fight against plastic contamination in U.S. cotton.

Technical Abstract: A commercial cotton contamination cleaner developed and used to combat the plastic contamination problem in Chinese cotton was tested to compare its performance at removing typical plastics found in U.S. cotton to that of conventional cotton gin seed cotton cleaners. Seed cotton “spiked” with pieces of shopping bags, single-layer non-tacky round module wrap (RMW), and three-layer RMW of various sizes was introduced into the machines. Overall, the contamination cleaner was more effective at removing plastic contamination than a conventional cotton gin stick machine and inclined cleaner. Increasing the airflow to the contamination cleaner improved plastic removal. Overall capture of plastic across all sizes and types increased from 16 to 48% when airflow was increased from 17,500 to 30,200 m3/hr (10,300 to 17,800 ft3/min). However, seed cotton captured with the plastic also increased from 1.4 to 34 kg (3 to 75 lb) per bale. Shopping bag material and one-layer non-tacky RMW (lighter, pliable) were more effectively removed than three-layer RMW (heavier, stiffer), and smaller plastic pieces were more effectively removed than larger pieces. All the machines tested removed about the same amount of cotton trash (about 13.6 kg or 30 lb per bale).