Trends in Sweden for closed cycle recovery of TCF bleach filtrates in integrated kraft paper production

During the last two years, three mills in Sweden with integrated kraft pape r production have started to produce totally chlorine free bleached pulp wi th bleach plant filtrate recirculation and recovery. Each plant has a moder ate production rate of 300-500 a.d. tons/day. Two plants are bleaching birc h wood The third is designed for campaigns with birch and pine wood. Modera te final brightness levels, introduction of bleaching on site, and environm ental requirements make a "closed cycle" TCF bleaching plant that includes a reasonable amount of chlorine free filtrate a logical choice. The limited pro,,portion of bleach pulp at 10%-40% of the total pulp production was al so a factor into the decision. All three bleach plants use short TCF bleach ing sequences without ozone. Two plants use oxygen delignification, treatme nt with chelating agents, and pressurized peroxide stages. The third mill u ses no oxygen delignification.