With the help of neat flow sheet explain the manufacturing process of cotton cloth. Using cotton as raw material.
1 Answer
  1. An integrated cotton textile mill produces its own yarn from the raw cotton.
    1. Production of yarn from raw cotton includes steps like opening and cleaning, picking, carding, drawing, spinning, winding and warping. All these sequences are dry operations and as such do not contribute to the liquid waste of the mill.
    2. In slashing, the yarn is strengthened by loading it with starch or other sizing/substances. Waste originates from this section due to spills and the floor washings at the weak end.
    3. After slashing the yarn goes for weaving. The prepared cloth now requires scouring and desiizing to remove natural impurities and the slashing compounds.
    4. Caustic soda, soda ash, detergents etc are used in scouring in Kier boilers.
    5. Replacement of soap used in scouring by low BOD detergents may reduce BOD load by 35%.This section contributes about 50% of total pollution load.
    6. Bleaching operations use oxidizing chemicals like peroxides and hypochlorites to remove natural colouring materials. This section contributes about 10% of total pollution load.
    7. Mercerising consists of passing the cloth through 20% caustic soda solution. The process improves the strength, elasticity, lustre and dye affinity.
    8. Dyeing may be done in various ways using different types of dyes and auxiliary chemicals.
    9. Classes of dyes used include vat dyes, developing dyes, naphthol dyes, sulfur dyes, basic dyes, direct dyes etc.
    10. Colour from the dyes vary widely and although those are not usually toxic, they are esthetically objectional when they impart colour in the drinking water supplies.
    11. The finishing section imparts various finishes to fabrics. Various types of chemicals are used like starches, dextrines, natural and synthetic waxes, synthetic resins etc.

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