Application of Extended DLVO Theory, IV: Derivation of Flotation Rate Equation from First Principles
✍ Scribed by Roe-Hoan Yoon; Laiqun Mao
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 251 KB
- Volume
- 181
- Category
- Article
- ISSN
- 0021-9797
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✦ Synopsis
A flotation model was developed by considering both hydrodyties involved in the three-phase phenomenon. For this reason, namic and surface forces involved in the process. The hydrodymost of the flotation models developed in the past are empirinamic forces were determined using a stream function and then cal (1-3). A few investigators attempted to model the proused for estimating the kinetic energies that can be used for thincess by considering hydrodynamic parameters but ignoring ning the water films between bubbles and particles. The kinetic surface chemistry parameters (4, 5). Part of the difficulty energies were compared with the energy barriers created by surface lies in the lack of information concerning the latter. Howforces to determine the probability of adhesion. The surface forces ever, recent advances made in the measurement of surface considered included ion-electrostatic, London-van der Waals, and hydrophobic forces. Due to the insufficient information available forces using a surface force apparatus (SFA) and an atomic on the hydrophobic forces for bubble-particle interactions, contriforce microscope (AFM) revealed new information that is butions from the hydrophobic force were back-calculated from the essential for modeling flotation, particularly on those not values of the flotation rate constants determined experimentally considered in the DLVO theory. It has been shown that the with methylated silica spheres. The results show that the hynon-DLVO forces such as hydration (6, 7) and hydrophobic drophobic force constants ( K 132 ) for bubble-particle interaction forces (8, 9) play an important role in the coagulation and are larger than those ( K 131 ) for particle-particle interactions but dispersion of fine particles in aqueous media and that the smaller than that ( K 232 ) for air bubbles interacting with each other hydrophobic force is the major driving force for bubblein the absence of surfactants. The K 132 values determined in the particle adhesion (10-12). Therefore, modeling flotation present work are close to the geometric means of K 131 and K 232 , without considering contributions from the hydrophobic suggesting that the combining rules developed for dispersion forces may be useful for hydrophobic forces. The flotation rate equation force would be unrealistic. More recently, the role of longderived in the present work suggests various methods of improving range hydrophobic forces in flotation has been discussed flotation processes. ᭧ 1996 Academic Press, Inc.
(13), and the relationship between various hydrophobic Key Words: flotation rate equation; rate constant; hydrodynamforce parameters and water contact angle (which is a more ics; hydrophobic force; ion-electrostatic force; surface force; extraditional measure of hydrophobicity) has been established tended DLVO theory; kinetic energy; combining rule; bubble-parti- (14)(15)(16). These recent developments may be conducive to cle adhesion.