PARTICLE ELUTRIATION FROM A SPOUTED BED OF RECYCLED PULP FIBERS

Elutriation of small particles from a conical spouted bed of recycled pulp suspension, called elutriation spouting, was demonstrated experim entally. Both ink particles and pulp fines can be removed by an upward liquid stream with little fibre loss (about 2%). Elutriation spouting has potential applications in separating ink and/or fines from pulp s uspensions. The concentration of particles in the exit stream was meas ured continuously as a function of time using a spectrophotometer conn ected to a personal computer. The resulting elutriation curve exhibite d an approximately exponential decay. The elutriation coefficient, est imated using a first-order mode, was mainly dependent on the flow rate . increased the flow rate, by increasing the ratio of flow rate to min imum spouting flow rate (Q/Q(ms)) at the same inlet size and initial s olids hold-up or by operating at larger inlet diameter or larger initi al solids hold up at the same Q/Q(ms), increased the elutriation coeff icient. Operating at larger Q/Q(ms) increased fibre loss.