Influence of non-wetting conditions on aggregation of divided solids in liquid phase

Michel Cournil (1, 2, 3) , Frédéric Gruy (1, 2, 3) , Patrick Cugniet (1, 2, 3)

1 SPIN-ENSMSE - Centre Sciences des Processus Industriels et Naturels
2 GENERIC - Géochimie, environnement, écoulement, réacteurs industriels et cristallisation
3 LPMG-EMSE - Laboratoire des Procédés en Milieux Granulaires

We present here the main results of an experimental study of aggregation which was performed on two silica granular samples: one is naturally hydrophilic; the other has been made hydrophobic by superficial grafting of hydrophobic groups. Aggregation is studied in water-ethanol mixtures of variable compositions and followed by in situ turbidimetry at different stirring rates. The aggregation behaviors of the two samples are quite different. Aggregates of hydrophilic particles are small and fragile whereas aggregates of hydrophobic particles are large and particularly solid. Interpretation of these differences is presented; it is based on several elements: modeling of hydrophobic interaction and of aggregate morphology, modeling of the aggregate optical properties and determination of the aggregation and fragmentation rates. Essential modification introduced by non-wetting consists of the formation of gas bridges around contact points between particles in aggregates.

Mots clés: aggregation; fines particles; silica; turbidimetry; stirring rates; modeling

Domaines: Génie des procédés

Michel Cournil, Frédéric Gruy, Patrick Cugniet. Influence of non-wetting conditions on aggregation of divided solids in liquid phase. 9° Congrès de la SFGP (Société Française de Génie des Procédés), Sep 2003, Saint Nazaire, France. C2-8 pp. 63-70. ⟨hal-00838272⟩