• Steps towards minimizing contamination

    Chapter 2 - Cotton value addition - Extraneous contamination in cotton


    The contamination problem has to be attacked in cotton growing, picking and ginning. For this, a clear understanding of the actual nature and extent of contaminants present in different origins of cotton is necessary. It is also necessary to identify the dreadful type of contaminants which are difficult to remove even with electronic gadgets in the spinning process.

    In addition, it is necessary to determine the threshold level of these contaminants in raw cotton – the level at which the spinner will be comfortable. Preventive measures must be identified in cotton growing, picking, ginning and baling processes to minimize these contaminants in raw cotton bales and ensure that the contaminants do not exceed the stipulated threshold level.

    Manual contaminant cleaning at PT Apac, Indonesia

    A large Indonesian spinning mill, PT Apac Inti Corpora, collected comprehensive data on the nature and extent of contamination in different origins of cotton, based on systematic contamination removal from over 260,000 tons of cottons in eight years.

    This company consumes a large quantity of raw cotton (about 125–130 tons per day), imported from different countries, for the production of 100% cotton yarns and blends, greige fabrics and denim fabrics. They started manual cleaning of raw cotton to get rid of the contaminants and minimize complaints from their customers. About 100 tons of different cottons used for ring spinning are cleaned manually every day by a huge workforce and the contaminants thus collected are analysed.

    Manual cleaning lines are designed by PT Apac in such a way as to easily detect even very tiny contaminants in raw cotton bales. The operators engaged in the manual cleaning are given a comfortable seat, good table and proper lighting. A part of the table has wire mesh to remove dust from the cotton, and a part has a smooth white surface to detect colour contamination. Up to 40 operators are engaged in each line, with a conveyer belt running in between two rows of tables (see figures 2.20–2.25).

    Operators pick up very small tufts from the bales, open the tufts by hand and search for contamination. The contaminants detected are duly discarded in to the waste bags and the cleaned cotton is thrown to the conveyer. White polypropylene, oil, shiny spots, fungi, etc. are detected at the end of the conveyer under UV light. The cotton thus cleaned is re-baled, wrapped with cotton wrappers and stored with proper identification of shipment, type, etc.

    Figure 2.20: General view of manual cleaning line



    Figure 2.21: Cleaning table with wire mesh and white top



    Figure 2.22: Contamination collected in waste bags



    Figure 2.23: Cleaned cotton on the conveyer



    Figure 2.24: UV checking



    Figure 2.25: Repacked bales



    The main advantage of this manual cleaning is effective removal of contaminants, to the extent of 98%–99%. Other advantages are: very thorough blending, good opening, less fibre damage, effective removal of sand and dust, reduction in stickiness, reduction in load on electronic clearers in winding and improved winding efficiency, accurate information on the nature and extent of contamination in cotton shipments and, finally, authentic feedback to the cotton suppliers.

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    Cotton Exporter's Guide

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