New laboratory approach for evaluating kraft mill pitch deposit control additives

The deposition of synthetic pitch emulsions onto transparent plastic films was observed with a microscope. Direct counting of deposited particles versus time gave deposition kinetics. Without deposit control additives almost every pitch droplet which approached the surface deposited. Treatment with nonylphenol ethoxylates, a standard class of pitch control additives, decreased the rate of deposition but failed to prevent it entirely. …