Study of Flotation Deinking Efficiency of Old Newspaper and Old Magazine

The effect of flotation parameters such as flotation consistency, temperature, flotation time, air to pulp ratio, velocity of pulp flow (turbulence level), and pH on old newspaper/old magazine deinking efficiency was studied by using a laboratory deinking cell developed by ourselves. The optimized flotation conditions were: flotation consistency 1.2%, 50 degrees C, 6min, air to pulp ratio 50%, velocity of pulp flow 3.5m/s and pH 8.5. By using the optimized flotation conditions, the deinked pulp brightness could reach 59.15%ISO, 10.18%ISO higher than that of the control, the effective residual ink concentration was 234.65 mg/kg, which less heavily than 875.56 mg/kg of the control, theoretical deinking efficiency was up to 84.42%.