Kraft pulp bleaching with molybdenum activated acid peroxide (P Mo stage)

摘要

Optimum conditions to run the PMo stage for bleaching eucalyptus kraft pulp were 90 ?oC, pH 3.5, 2 h, 0.1 kg/t Mo and 5 kg/t H2O2. The PMo stage efficiency increased with decreasing pH (1.5-5.5) and increasing temperature (75-90 ?oC), time (2-4 h), and hydrogen peroxide (3-10 kg/t) and molybdenum concentration (0.1-0.4 kg/t). The implementation of the PMo stage, as replacement for the A stage, decreased total active chlorine demand of the OAZDP sequence by 6 kg/t to reach 90% ISO, both in laboratory and mill scale. Such practice resulted in decreased bleaching chemical costs to produce fully bleached pulp of 90% ISO.