Interfacial Phenomena in Deinking, 1993 Pulping Conference Proceedings

Flotation has been one of the most important ways to remove ink particles from slushed pulp of wastepaper. To ensure a successful flotation deinking operation, formation of stable ink particle-air bubble aggregates is an essential requirement. In this study, a theoretical model is developed to determine the stability of the ink particle - air bubble aggregates by considering buoyancy, gravity, capillary forces and other external dynamic stress exerted on the ink particle - air bubble aggregates. Calculation was carried out based on the equations derived and parametric values estimated or measured. The results clearly indicate the significant importance in determining the particle-bubble aggregate stability of the following factors: liquid surface tension, surface free energy of ink particle, ink particle size, air bubble size and the external turbulence. Based on theoretical calculation, discussions were made on various factors affecting the stability of ink particle-air bubble aggregates and their implication on flotation deinking.