Elemental chlorine free bleaching process

In 1990 about 10% of the world s chlorine production (ca. 3.4 million tonnes) was used for pulp and paper [329]. As a consequence of the change-over to chlorine free bleaching processes, the use of elemental chlorine was drastically reduced to 2.95 million tonnes in 1994, and is anticipated to be 1.9 million tonnes in 2000) [319]. In 1983 in the United States 13 % of the chlorine production was used for pulp and paper, 1994 9%, 2000 6%, 2010 0% (estimated). In areas like Canada or Western Europe, the reduction was even more drastic 1998, in Western Europe 18 000 tonnes of chlorine went into this production, accounting for only 0.2 % of the production [330],... 

Chemical pulp bleaching has undergone significant process changes since around 1990. Until that time, nearly every chemical pulp mill that had used bleaching had incorporated elemental chlorine (Clj) into some of its processes. Because of environmental and health concerns about dioxins, U.S. pulp mills now use elemental chlorine free (ECF) and total chlorine free (TCF) bleaching technologies. The most common types of ECF and TCF are shown in Table 21.5. The difference... 

Common Chemicals Used in Elemental Chlorine Free (ECF) and Total Chlorine Free (TCF) Bleaching Processes... 

ECF [Elemental chlorine free] A generic term for pulp-bleaching processes which use chlorine dioxide and other oxidants in place of elemental chlorine. See also TCF. 

The case study presented here deals with a pulp and paper production process. The plant produces Bleached Eucalyptus Kraft Pulp, using the ECF process (Elemental Chlorine Free). The Kraft pulping process is performed in two different phases, which influence the final pulp quality the cooking process of wood chips (eucalyptus globules) followed by the pulp bleaching. The cooking process is the phase that most contributes to the preservation of the main pulp characteristics, which, in turn, will ensure high quality paper. 

Since it became clear that the direct use of chlorine in the bleaching of pulp and paper leads to highly poisonous chlorinated organic species in the waste water, chlorine dioxide is used instead in the so-called ECF (Elemental Chlorine Free) process. The competing process is the TCF (Total Chlorine Free) process, which uses peroxides [11],... 

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