DEINKING LASER-PRINT PAPER USING ULTRASOUND

Laser-printed pulp is distinguished by large, flat, platelike ink part icles. These particles are much more difficult to remove than conventi onal ink particles. It was shown in this research study that ultrasoun d waves can split apart and loosen these tenacious particles. Use of a particle-size analysis system suggested that frequencies of 22 kHz, 3 4 kHz, and 54 kHz each affected particles of different size ranges. Th is implies that a commercially feasible ultrasound deinking process mi ght be developed as a stand-alone treatment method for laser-print pap ers or as a polishing step for mixed post-consumer wastes to improve t he overall pulp quality.