Clarifying the Flotation Cell Rejects: A Process Application to Close the Deinking Plant Water Circuits, 1994 Pulping Conference Proceedings

L. Menke, O. Heise, C. Otto

Water circuits are a crucial part of every deinking plant process. They have a significant impact on the quality of the pulp and the economical runnability of the plant (i.e. effluent discharge fees).

The handling of the deinking cell’s rejects is a problem in many recycling plants. Instead of discharging these rejects to the final effluent plant, which increases its capacity requirement, there is the process option to pre-thicken and clarify the rejects with dissolved air flotation. The pre-thickened rejects can be easily pressed and the clarified water is of adequate quality to be recycled back to the system.

This paper discusses the integration of this technology into the reverse flow water circuit concept. Further, chemical consumption and water quality data based on trial work done at the Voith Technology Center will be presented. The paper includes an overview of the role and mechanism of chemicals in clarifying the flotation cell rejects.