EFFECTS OF PROCESS VARIABLES IN FLOTATION DEINKING OF OLD NEWS PRINT

Abstract

Optimization of flotation process is attempted using ONP. Optimization of flotation time- and chemicals dosages variation has been done. It appears that beyond 10 minutes flotation time that removal of ink is not significant. The RPM of rotor of flotation cell or indirectly the airflow rate should be maximum to have -maximum floatation efficiency. It is found that 2000 RPM gives maximum flotation efficiency_ Consistency of flotation should be 1% to have great probability of ink particles attachment due to their high concentration. Effects of surfactants in flotation deinking operation of ONP have been studied using 4 surfactants namely Oleic acid, Palmitic acid, Stearic acid and Jinex. It is observed that Oleic acid, Palmitic acid, Stearic acid has optimum dosage after which the deinkability factor decreases with increasing dosage. In case of Jinex, with the increase in its dosage, the deinkability factor goes on increasing resulting in better quality pulp while the loss of fines and fibers also increases. It appears that Jinex also accumulates dust or fines along with ink to form the medium size agglomerate, which can be carried away with the air bubble as foam with the increase in dosage_ The ink agglomerate size increases with increase in dosage of Oleic acid, Palmitic acid, Stearic acid resulting in its reversal back to the pulp beyond optimum dosage.