Emulsions in the flotation deinking of coated paper

The effect of a model emulsion deinking agent containing stearic acid dispersed with nonionic surfactant (polyethyleneoxide alkyl ether) on three different types of coated papers was investigated in alkaline and neutral conditions Papers contained kaolin, kaolin + ground calcium-carbonate (GCC) and gypsum + kaolin pigments. The papers were also deinked with the emulsion components separately, i.e. dispersant, stearic acid and also with Na-stearate. The model emulsion used did not give any significant advantage in the deinking of coated paper neither in neutral nor in alkaline conditions. Although different types of drinking agents were used, the effect of system pH an pulp components and dissolving of surface active material dominated over the effect of chemicals. The drinking efficiency of emulsions is probably better seen in the deinking of newsprint and in conditions where the mechanical ink detachment farces are weak (low consistency pulpering).