Flotation Deinking of Toner-Printed Papers Using Frother Spray, 1998 Pulping Conference Proceedings

We experimentally studied a novel approach using a simple frother delivery device, i.e., a spray atomizer, in flotation deinking of toner printed papers to control several key process variables that affect ink removal, froth stability, fluid dynamics in froth, fiber contamination, fiber and water losses, and frother consumption. Instead of adding frother into the pulp slurry directly before flotation in the conventional process, a pressure atomizer was used to spray the frother solution from the top of the flotation column during flotation. Results obtained in a laboratory column flotation cell indicated that the frother spray approach can reduce fiber loss by 50%, water loss by 75%, and frother consumption by 95% without sacrificing deinking efficiency. The proposed approach can also prevent fiber from contamination by the process frothing agent. More importantly, this study developed a simple method to mechanically control froth stability when the physicochemical properties of the pulp source vary.