Hydrodynamics of shear floccuation.
Spears-DR; Stanley-DA; Sharma-SK
Advances in Filtration and Separation Technology: New Filtration and Separation Equipment, Annual Meeting of the American Filtration Society, May 10-14, 1992, Chicago, Illinois. Peters-RW, ed., Des Plaines, IL: Cahners Publishing Company, 1993 Jan; 6:433-443
Shear flocculation of silica can be caused by stirring at high speeds in the presence of a collector. The kinetics of shear flocculation can be described in terms of a probability of shear flocculation, which is the product of a series of probabilities describing the shear flocculation process. 439 The kinetics of shear flocculation indicates two distinct reactions: 1), rapid floc growth, and 2) a region in which floc growth and floc decay are in equilibrium. The extent of growth is dependent on collector dosage, which increases the number of surface sites available for attachment and interparticle interaction. High collector dosages not only permit large floc growth, but increase floc stability. Agitation is necessary to permit particles to have sufficient momentum to overcome the energy barrier keeping particles separated. Agitation can also cause large number of collisions which can lead to aggregation despite unfavorable conditions such as poor collector coverage. However, floc stability is inversely proportional to the shear rate, and a too-intense shear rate can cause floc disruption.
Mineral-processing; Minerals; Metal-compounds; Metal-mining; Metal-refining
Book or book chapter
Advances in Filtration and Separation Technology: New Filtration and Separation Equipment, Annual Meeting of the American Filtration Society, May 10-14, 1992, Chicago, Illinois