pulpand paper production333333333333333333333.pptx

pulp

1. Pulp is a commercial cellulose derived from bamboo, bagasse, wood, etc., by mechanical or chemical methods. Pulp Methods of Production Groundwood Chemical Semi chemical Groundwood -debarked wood is mechanically shredded to form fibers suitable for production of newsprint, toweling , toilet tissues, and cheap paperback books where strength and ease of bleaching are not important. Chemical: The cellulose from wood is freed from lignin and other non-cellulose ingredients by reaction with chemical reagents. The two important process are sulfate (Kraft) and sulfite process. Semi chemical: wood chips are given a mild chemical treatment with dilute mixture: sulfite, sulfate, caustic soda, and/or soda ash reagents. The wood is softened sufficiently to allow mechanical separation of fibers without excess power. A high yield of 65-90% with a somewhat better quality than groundwood pulp is the reason for the increasing interest in semichemical pulp as a substitute for groundwood pulp. Sulfate pulp Sulfite pulp