EFFECTS OF FIBER LENGTH AND COARSENESS ON PULP FLOCCULATION

The effects of fiber length and coarseness on pulp flocculation were s tudied by measuring the mass uniformity of fiber suspensions at rest a fter turbulence decay. Increasing fiber length led to a decrease in un iformity by increasing the degree of fiber contact (crowding factor) a nd floc size. Increasing coarseness at the same fiber length and crowd ing factor further diminished uniformity. Mixtures of long and short f ibers of a given length-weighted average length gave the same nonunifo rmity as individual fractions of the same fiber length. The uniformity obtained at a given fiver length was the same for suspensions contain ing fibers of equal length or mixtures of long and short fibers of the same length-weighted average length. Both fiber length and coarseness also affected fiber mobility, which reflects floc strength. Mobility was not tested, but it is postulated that, like uniformity, it is a ke y factor in paper formation on commercial machines.