Retention of Fine Particles in a Fiber Mat During Washing, 1999 International Paper Physics Conference Proceedings

Terry Bliss, Martin Ostoja-Starzewski, Jaime Castro

Fine particles are usually retained in fiber mats by sieving. To date, no theory has combined fiber and mat characteristics into a predictive retention model. Average fiber-fiber clearance can be calculated quickly from mat porosity or consistency, and fiber coarseness, assuming that the fibers are straight, parallel, and equally spaced. A multilayer analytical retention model developed during this study predicts retention within a thick fiber mat by modeling retention as particles pass through a series of very thin fiber mats. A suspension of 5-75 mm toner particles was percolated through rayon fiber mats. The model’s prediction approached the experimental data only when the ratio of particle diameter to fiber diameter increased toward 2.0, the upper limit within the rayon fiber mat data set. Retention was also experimentally determined on the macro scale with simulated fiber mats, through which 4 to 20 mm beads were dropped. The particle diameter was at least 2.2 times the fiber diameter for all of the macro scale experimental data, explaining the much better fit of the data from those experiments to the model’s predictions. This study also shows that a simple semiempirical experimental model can reliably predict particle retention across a wide range of conditions.