| 摘要 |
Bleached cellulose fibre pulp are prepd. by first cooking a cellulose fibre material, pref. wood, then sepg. the pulp from the spent cooking liquor (I). (I) is then evapd., and burnt in an oven to give a melt which is dissolved up to give a green liquor (II). One portion of (II) is treated with caustic and recycled to the cooking stage; one portion is processed to make NaCO3 and a third is used to generate H2S. This is oxidised (partly) to H2SO4, (part of) which is reacted with MClO3 and MCl (when M is alkali metal, esp. Na) to give ClO2 and M2SO4. The M2SO4 is used as feed for the oven. Pref. the CO2 used for NaHCO3 prodn. is provided by combustion gases from the oven, and the ClO2, esp. as aq. soln., is used to bleach the pulp. By including a S recovery/recycle system max. utilisation of chemicals is achieved with minimisation of chemical losses and pollution. |
