Evaluation of the Flocculation and Reflocculation Performance of a System with Calcium Carbonate, Cationic Acrylamide Co-polymers, and Bentonite Microparticles

Flocculation, flocs resistance, and reflocculation capacity of a precipitated calcium carbonate (PCC) suspension with cationic polyacrylamides (C-PAMs) varying in charge density and degree of branching were investigated in previous studies and correlated with retention and drainage performance in papermaking. In this study, the reflocculation performance of the PCC suspension was investigated using the same C-PAMs, in combination with microparticles, since microparticle retention systems have been widely used in papermaking to improve reflocculation of the suspension. Moreover, flocculation and reflocculation performance evaluated using the laser diffraction spectroscopy (LDS) technique was compared with that obtained using focused-beam reflectance microscopy (FBRM) to monitor the process. The coupling of these two techniques allows a detailed analysis of the reflocculation process, including evaluation of the flocs structure before and after the reflocculation stage.