Characterization of Repulper Operation for Newsprint Deinking, 1998 Pulping Conference Proceedings

Defibering, ink removal and particle comminution in hydraulic repulpers is achieved by imposing forces on the paper/fibre through the action of the rotor. By assuming that direct rotor-fibre contact accounted for the pulping action, Bennington et al. (1997) developed a model that described paper deflaking. The extent of defibering is proportional to the accumulated area of contact between the suspension and rotor, with the rate of deflaking determined by the strength of the material repulped (the wet tensile strength) and the force applied to the suspension by the rotor. The equation was validated for a range of paper furnishes and pulper operating conditions. In this paper a number of outstanding issues were examined. The validity of the model is confirmed for rotors designed to achieve different swept areas, and the effect that the volume of suspension treated has on deflaking performance examined. The model is also shown to hold for a high-intensity mixer that achieves turbulence within the suspension although the two model parameters required adjustment. The equations are then used to describe the repulping of mixtures of wastepaper furnishes.