Removal of sheet plastic materials from seed cotton using a cylinder cleaner

Authors: Hardin Iv, Robert; Byler, Richard

Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/10/2016
Publication Date: 12/30/2016
Citation: Hardin IV, R.G., Byler, R.K. 2016. Removal of sheet plastic materials from seed cotton using a cylinder cleaner. Journal of Cotton Science. 20(4):375-385.

Interpretive Summary: US produced cotton is among the cleanest available in the world. However, occasionally pieces of sheet plastic are found in cotton bales produced in the US. A previous study showed that the entire system of normally employed cotton cleaning and ginning equipment is not very efficient in removing plastic which has become entrained in the seed cotton. The purpose of this work was to examine how selected operating conditions affect the sheet plastic removal efficiency and fiber loss of one type of gin cleaning machine, the cylinder cleaner. This work was done in two parts using a research-scale cylinder cleaner. In the first part, two types of plastic were each tested, while varying air flow rate through the machine, seed cotton processing rate, and size of plastic contaminant. In the second part, only one plastic type was used, but two cotton cultivars were each tested. An additional variable, cylinder rotation speed in the cylinder cleaner, was evaluated. Mathematical models were developed predicting the plastic removal and fiber loss for the included independent variables. In both parts of the study, plastic removal increased linearly with increasing air flow rate and decreasing size of the plastic pieces. The effect of seed cotton processing rate on plastic removal was less significant than the effect of air flow rate or plastic size in the first part and was not statistically significant in the second part. The plastic originating from shopping bag material was more effectively removed than the module wrap material. More plastic was removed at lower cylinder cleaner speeds, and the cotton cultivar did not significantly affect the plastic removal rate. This work shows how relatively small adjustments to the operation of this machine in a cotton gin would significantly increase the removal of smaller pieces of plastic which may be entrained in the seed cotton. Reduction of plastic contamination will improve the value of the cotton for cotton mills.

Technical Abstract: US produced cotton is among the cleanest available in the world. However, occasionally pieces of sheet plastic are found in cotton bales produced in the US. A previous study showed that the entire array of normally employed cotton ginning equipment is not very efficient in removing plastic included in the seed cotton. The purpose of this work was to examine how selected operating conditions affect the sheet plastic removal efficiency and fiber loss of one type of gin cleaning machine, the cylinder cleaner. This work was done in two parts using a research-scale cylinder cleaner. In the first part, two types of plastic were each tested in a central composite design, varying air flow rate through the machine, seed cotton processing rate, and size of plastic contaminant. In the second part, only one plastic type was used, but two cotton cultivars were each tested in a central composite design. An additional response surface variable, cylinder rotation speed, was evaluated. Mathematical models were developed predicting the plastic removal and fiber loss for the included independent variables within the ranges studied. In both parts of the study, plastic removal increased linearly with increasing air flow rate and decreasing size of the plastic pieces. The effect of seed cotton processing rate on plastic removal was less significant than the effect of air flow rate or plastic size in the first part and was not statistically significant in the second part. The plastic from shopping bag material was more effectively removed than the module wrap material. More plastic was removed at lower cylinder cleaner speeds, and the cotton cultivar did not significantly affect the plastic removal rate.