PROCESS FOR DELIGNIFYING AND BLEACHING CELLULOSE PULP WHEREIN THERE IS A REDUCED FORMATION AND DISCHARGE OF HALOGENATED ORGANIC COMPOUNDS IN THE WASTE LIQUOR; PULP TREATED WITH A TRACE METAL COMPLEXING AGENT AND THEN WITH A PEROXIDE AGENT

摘要

The present invention relates to a process for delignification and bleaching of chemically digested lignocellulose-containing pulp for reduced formation and discharge of halogenated organic compounds, while preserving the pulp quality, where the prebleaching with halogen-containing bleaching agent is replaced by a treatment, in a first step, with the addition of a complexing agent at elevated temperature and at a pH from 3.1 to 9.0, and in a second step, by using a peroxide-containing compound under alkaline conditions, whereupon spent liquor from the final bleaching with halogen-containing compounds is recycled to the first or second step of the halogen-free prebleaching.