Cationic microparticle based flocculation and retention systems

Two types of microparticles, cationic silica particles (CSP) and cationic p olymeric microparticles (CPMP), were used as flocculants and retention aids for solid suspensions in water and pulp, respectively The solid suspension s used in this study include both positively and negatively charged precipi tated calcium carbonate (PCC) and negatively charged polystyrene latex. It was found that CPMP was not an effective retention aid for positively charg ed PCC suspension in pulp if it was used alone. However, the retention of P CC was improved when negatively charged PCC was used. The combination of ca tionic microparticle systems (CPMP and CSP) with either cationically or ani onically charged water-soluble polyacrylamides could significantly improve the flocculation and retention. The possible mechanisms of flocculation of solid suspensions with different dual-flocculant systems were discussed. (C ) 2000 Elsevier Science B.V. All rights reserved.