The Study of a Laboratory Screw Press Washer as a Means of Deinking Offset Newsprint at High Consistencies

The objective of this thesis is to study a laboratory horizontal screw press washer as an effective, yet economical, means of deinking offset newsprint wastes at high consistencies. The theoretical advantages of utilizing a high consistency deinking process include minimal water consumption, reduced and more concentrated filtrate volumes, low effluent solids and fiber loss, and minimal space requirements. The disadvantages include a relatively high unit power consumption, high capital cost, sometimes an inefficient amount of fillers and fines removed, and ink particles may get trapped at consistencies greater than 18%. Results proved many of these theoretical advantages and disadvantages. Also, the screw press did prove to be an effective piece of equipment for removing offset ink at high consistencies. However, further work concerning the screw press is recommended as results were not able to be duplicated due to limiting time factors and mechanical failures of the equipment