The Effects of Low Temperature Cooking on the Deinking of Groundwood

An experiment was designed to lower the temperature of the cooking stage in the deinking of groundwood. The cook chemicals consisted of sodium meta-silicate, sodium carbonate, hydrogen peroxide and surfactants. The pulp was cooked over a temperature of 50°F-130°F. The pulp was washed on a laboratory sidehill screen and brightness pads were made. The object of the experiment was to reduce the cook temperature and use additional surfactant to maintain the brightness. Maximum brightness values were found a 0.1% surfactant and 110°F, and 0.3% surfactant and 90°F. A cost analysis revealed that a system can operate at slightly elevated temperatures and low surfactant level. This type of system is more economically feasible than operating at low temperatures and higher surfactant level. Keywords: Deinking, washing, secondary fiber, newsprin