Oil-assisted agglomeration for toner deinking: Population balance model and experiments



This study examines the selective agglomeration of hydrophobic toner particles from a repulped paper fiber slurry by adding an immiscible oil that preferentially wets the toner particles. Effects of cationic starch additives, agitation rate, time, temperature and oil composition are examined experimentally in terms of the dynamic and steady-state evolution of the particle-size distribution produced. A simple, but effective, population balance model is solved numerically to simulate the agglomeration process and provides quantitative relationships between process variables and the effectiveness and rate of agglomeration. These relations are simple and clear. The process is shown to be controlled by the composite effect of the aforementioned variables on the aggregation and breakup rates, and the observed hehavior is understood in these terms. Practical recommendations for agglomeration, a process potentially useful for deinking toner-printed paper, are deduced from the results.