Effect of Flotation Parameters on Old Book Paper Deinking Efficiency

The effect of flotation parameters such as flotation consistency, temperature, flotation time, air to pulp ratio, and turbulence level (velocity of pulp flow) on old book paper deinking efficiency was studied by using a high-consistency laboratory pulper and a laboratory deinking cell. The optimized flotation conditions were: flotation consistency 1.2%, 50°C, 6min, air to pulp ratio 40%, velocity of pulp flow 5.0m/s. By using the optimized flotation conditions, the deinked pulp brightness could reach 77.01%ISO, 9.69%ISO higher than that of the control, the effective residual ink concentration was 175.26 mg/kg, which less than 437.84mg/kg of the control, deinking efficiency was up to 59.97%. After washing process, pulp brightness could reach 84.27%ISO, the effective residual ink concentration was 93.71 mg/kg, deinking efficiency was up to 78.60%.