The Differences Between Kraft Pulping And Soda-AQ Pulping Of Paper Mulberry

The supplies of material are shortage at present. It can be resolved by making good use of paper mulberry. One of the disadvantages during kraft pulping is the discharge of malodorous sulfide which causes the air pollution. The discharge of chloride water in bleaching is another serious pollution of pulping and paper making industry. In order to lighten the pollution, soda-AQ pulping and kraft pulping were applied to paper mulberry, and the CEH and TCF bleaching sequences were also used.Compared with the results of soda-AQ pulping and kraft pulping, conclusions can be drawn as below:1. The compatible conditions for kraft pulping of paper mulberry were: total alkali charge 17%, sulfidity 25%, liquor-to-wood 1:4, maximum temperature 170℃, time at cooking temperature 90 minutes, the kappa number of the pulp in the conditions was 26.16, the yield was 38.54. The compatible conditions for soda-AQ pulping of paper mulberry were: alkali charge 17%, AQ charge 0.1%, maximum temperature 170℃, time at cooking temperature 90min, liquor-to-wood ratio 1:4, the kappa number of the pulp in the conditions was 22.49, the yield was 46.43%.2. Along with the charges of alkali increase, the yield was increased, the kappa number was decreased. Compared with Kraft pulp, the kappa number of soda-AQ pulp was lower than Kraft pulp with in the same charge of alkali, which mainly caused by the different component of liquor.3. After the acid treatment, the kappa numbers of soda-AQ pulp and Kraft pulp were reduced. The dropping extent of Kraft pulp was larger than soda-AQ pulp, which indicated that in Kraft pulping, the content of HexA was higher than the content in soda-AQ pulp.4. There were more free fibers and fewer long fibers in soda-AQ pulp than Kraft pulp.CEH and OAPoP bleaching sequences were used for soda-AQ pulp and Kraft pulp. The results show that:1. The kappa number of Kraft CEH bleaching pulp was 6.0, the brightness was 76.7%SBD, and the p. c value was 1.81. The brightness of Kraft TCF bleaching pulp was 78.8%SBD, and the p. c value was 0.46. On the other hand, the kappa number of soda-AQ CEH bleaching pulp was 4.4, the brightness was 75.9%SBD, and the p. c vale was 1.98. The brightness of soda-AQ TCF bleaching pulp was 80.1%SBD, and the p. c value was 0.52.2. Compared with Kraft pulp, the brightness and the p. c value of soda-AQ pulp were higher when using OAPoP bleaching.