A model predicting filler retention from collision efficiency was developed and validated with a mill trial. The collision efficiency model for retention systems consisting of a high molecular weight polymer and microparticles was modified to include two different particles (fiber and filler) and the effect of polymer transfer. The collision efficiency is a function of the surface coverage of the solids (fiber and filler) by adsorbed and transferred polymer, and the surface coverage of microparticles on the polymer adsorbed layer. Filler retention was measured and compared to the calculated collision efficiency. The dosage of polymer, microparticle and the concentrations of filler and fibers were varied. The calculated collision efficiency was strongly correlated with the filler retention measured. The predominant variables affecting collision efficiency and filler retention are CPAM concentration, followed by bentonite dosage. The fast kinetics of polymer adsorption onto fibers and polymer transfer, caused by filler deposition/detachment, govern collision efficiency and filler retention. Filler retention is best optimized by controlling the polymer and microparticle surface coverage.
|Number of pages||7|
|Journal||Nordic Pulp & Paper Research Journal|
|Publication status||Published - 1 Jan 2001|
- Filler retention