TOP QUALITY DEINKED PULP FROM MIXED OFFICE WASTE BY HIGH-TEMPERATURE PEROXIDE BLEACHING - HIGH-TEMPERATURES IMPROVE THE EFFICIENCY OF PEROXIDE BLEACHING

Peroxide bleaching at high temperatures has proven to be very successf ul in bleaching of deinked mixed office waste pulp. The high temperatu re results in a higher bleaching rate and an optimal utilization of hy drogen peroxide. The result is a better decoloring of chromophores pre sent in lignin and dyes and, thus, higher brightness at lower peroxide consumption level than in standard peroxide bleaching. Our earlier la boratory results have been confirmed in mill trials. We have also exte nded our studies to mixed office waste pulps containing more than 30% mechanical fibres. Also these pulps can be bleached with peroxide at t emperatures above 100oC, if the metal content is controlled.