We have a long history of bamboo papermaking in China. Bamboo fiber morphology and chemical composition are special. The average fiber length is long, and the fiber cell wall microstructure is special. The strength development performance during pulping is good, giving the bleached pulp good optical properties of high opacity and light scattering coefficient. The lignin content of bamboo raw materials (about 23%-32%) is high, which determines the high alkali amount and sulfidation degree during pulping and cooking (the sulfidation degree is generally 20%-25%), which is close to coniferous wood. The high hemicellulose and silicon content of the raw materials also brings certain difficulties to the normal operation of the pulp washing and black liquor evaporation and concentration equipment system. Despite this, bamboo raw materials are still a good raw material for papermaking.
The bleaching system of large and medium-sized chemical pulping plants of bamboo will basically adopt TCF or ECF bleaching process. Generally speaking, combined with deep delignification and oxygen delignification of pulping, TCF or ECF bleaching technology is used. Depending on the number of bleaching stages, bamboo pulp can be bleached to 88%-90% brightness.
Our bleached bamboo pulp tissues are all bleached with ECF (elemental chlorine free), which has less bleaching loss on bamboo pulp and higher pulp viscosity, generally reaching more than 800ml/g. ECF bleached bamboo tissues have better pulp quality, use less chemicals, and have high bleaching efficiency. At the same time, the equipment system is mature and the operating performance is stable.
The process steps of ECF elemental chlorine-free bleaching of bamboo tissues are: first, oxygen (02) is introduced into the oxidation tower for oxidative delignification, and then D0 bleaching-washing-Eop extraction-washing-D1 bleaching-washing are carried out in sequence after washing. The main chemical bleaching agents are CI02 (chlorine dioxide), NaOH (sodium hydroxide), H202 (hydrogen peroxide), etc. Finally, the bleached pulp is formed by pressure dehydration. The whiteness of the bleached bamboo pulp tissue can reach more than 80%.
Post time: Aug-22-2024
