Techniques for fractionating pulp fibers

Two methods have been investigated to determine the extent of separation of pulp fibers on the basis of fiber length and the difference in chemical composition of the chemical and mechanical pulps. Elutriation of fiber fines in a conical spouted bed of recycled pulp (elutriation spouting) was conducted experimentally to remove small fiber particles (fines) from the slurry. The pulp suspension was fluidized at different flow rates of water. The length of the fibers in the overflow and the bed was determined by using Kajaani FS-100 fiber length analyzer.;In another set up, experiments were conducted with the aim to separate mechanical pulp from chemical pulp using column flotation. It is well established that the difference in the chemical composition of chemical and mechanical pulp influences the wettabilty of the fibers and renders them hydrophobic or hydrophilic. Different dosages of surfactant were examined, which created the froth and helped in selectively entraining hydrophobic pulp (mechanical) in the bubble swarm. The more hydrophilic pulp (chemical) was left behind.