Bleaching in two stages of industrial chemi-mechanical pulps

The objective of the work is to optimize the bleaching with hydrogen peroxide of chemi-mechanical pulps to the cold soda water of implanted LATIFOLIADAS using a process in two stages. Pulp of the factory Zárate de Celulosa Argentina S. A. Was used (pulp to the cold soda water of SALICACEAS mixtures and eucalyptus). The variables were: consistency (15 to 25%), total peroxide concentration (4.32 to 7.7% bps) and temperature (61.5 to 78.5°C). The total amount of peroxide was distributed in equitable form in each stage. The total alkalinity in all the cases was of 4.2% bps (50% in each stage). The physical-mechanical and optical tests were mae according to TAPPI standards. The natural reversion of the brightness was moderate after a year of storage of the pulp. The parameters of colour were moderate, a, b, and the quotient k/s was moderate and calculate for the REVENNIDAS pulp. The peroxide consistency, temperature and load have significant influence in the obtained brightness, but they do not have it in the physical-mechanical resistance. The maximum hit brightness was of 78.7% ISO using the extreme conditions of the process. The minimum reversion is presented by the bleached pulp to 75°C, 6.6% of H2O2 and 17% of consistency.