Förfarande för blekning av kemisk, mekanisk, kemisk-mekanisk och/eller återvunnen massa med peroxid

摘要

Fibre intermediates are bleached with chlorine free chemicals by using peroxide together with, if desired, other bleaching chemicals in two phases. Heavy metals are removed by acidifying or treating with a complexing agent. The intermediate is then bleached in at least one multistage peroxide phase, at least the 1st stage of which is pressurised.