Effect of Process Variables in Laboratory Deinking Experiments, 1992 Pulping Conference Proceedings

It is difficult to model mill deinking operations on a laboratory scale. The effect of scale-up of laboratory experiments to a pilot mill scale (from 20 grams of furnish to 250 pounds, a scale-up factor of 5,675) indicates:

* laboratory tests can serve to pre-dict relative surfactant deinking, yield loss, and foaming behavior

* laboratory tests can give approxi-mate predictions of handsheet brightness under mill conditions

* improved laboratory deinking test procedures and apparatus are needed to predict yield losses accurately in mill operations.

Laboratory test conditions can greatly affect the results of deinking experi-ments. A series of laboratory tests were performed using a model of a flotation-wash deinking process. Handsheet brightness increased with decreasing flotation cell consistency of a 70:30 newsprint:magazine pulp slurry. Yield losses increased with decreasing flotation cell pulp consis-tency. Increased consistency in the pulping step did not substantially affect handsheet brightness or yield loss.

Increased content of clays and fillers in the furnish generally leads to increased yield losses in both flota-tion and washing steps of deinking experiments.