Verfahren zur Erhöhung des Weißgrades von Papierfaserstoff

摘要

To increase the whiteness of paper fibre material (P) recovered from used printed paper, the material (2) is given an intensive mechanical working with a specific working rate of at least 20 kW/ton with a material density of≥15% and a material temp. of≥40 degrees C. At the bleaching stage (3), the total pressure is≥1 bar with a bleaching time of at least 10 mins.. The majority of the ink particles are removed (4) from the fibres.