Medium Consistency Forward Cleaning Development for Laser Deinking Systems, 1994 Recycling Symposium Proceedings

Frank J. Sutman, lrenee J. Philippe, Peter LeBlanc

An efficient laser print deinking system has been developed for the removal of non-impact inks from office waste. This chemi-mechanical system relies on the chemical aggregation and densification of laser and xerographic ink toner particles. Once densified, the ink particles are then removed from the pulp via mechanical separation processes. Previous research and mill experience has shown that forward cleaning is the most efficient means of ink removal from the pulp.

Conventional forward cleaners have high removal efficiencies at 0.5-0.6% feed consistency. Efficiency usually drops as consistency increases. This paper reports on a series of pilot scale experiments which developed a medium consistency centrifugal cleaner. The cone produced a treated laser ink removal efficiency of 93% at a feed consistency of 1.2%. This allows for a less costly deinking system. It also requires about one-half of the water handling and treatment of a conventional low consistency system.