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TJ Heindel

Publications and source records attributed to TJ Heindel.

3 recordsLinked to original sources

An Approximate Analytical Expression for the Probability of Attachment by Sliding.

The focus of this paper is on the flotation microprocess of attachment by sliding, considered to be an important microprocess in flotation separation. A detailed discussion is provided as to which forces are important for this microprocess during flotation deinking. By including the resistive force due to film drainage, the gravitational force, and the flow force between the bubble and particle, and accounting for both Stokes and non-Stokes flow conditions, a closed-form approximation for the probability of attachment by sliding (P(asl)) has been developed. The expression presented here is a function of fluid properties, bubble and particle physical properties, and the ratio of the initial-to-critical film thickness separating the bubble and particle (h(0)/h(crit)). Using this result, it is shown that P(asl) generally decreases with increasing h(0)/h(crit) and increases with increasing bubble and particle radii and particle density. However, local minima are observed. Additionally, the transition from Stokes to non-Stokes flow conditions results in an abrupt transition in the P(asl) predictions. Copyright 1999 Academic Press.

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Exact and Approximate Expressions for Bubble-Particle Collision.

The flotation microprocess of collision is investigated and an exact expression for the probability of collision (Pc) is developed based on the intermediate flow of Yoon and Luttrell (1). This expression for Pc only assumes that the bubble and particle are spherical and that the particle radius is less than the bubble radius (i.e., Rp < RB). In addition to removing the requirement that Rp << RB, the influence of a particle settling velocity is also included in the model development. The expression for Pc is shown to be a function of three dimensionless groups: (i) the magnitude of the dimensionless particle settling velocity, ||G ||; (ii) the bubble Reynolds number, ReB; and (iii) the ratio of particle to bubble radius, Rp/RB. The probability of collision model is compared to available experimental data and good agreement is shown. A parametric study is also completed for 0 </= ||G || </= 1, 0 </= ReB </= 500, and 0.001 </= Rp/RB < 1. In general, Pc is independent of ReB when Rp/RB less, similar 0.03, the particle settling velocity is important for small values of Rp/RB, and Rp/RB dominates as Rp/RB --> 1. Copyright 1999 Academic Press.

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A Theoretical Model of Flotation Deinking Efficiency

The associated probabilities of each microprocess occurring in flotation deinking are employed in the development of a kinetic or population balance-type model of the overall flotation process. The overall model contains two kinetic constants: The first, k 1 , governs the overall probability of a free ink particle successfully being intercepted by and adhering to an air bubble; the second, k 2 , is a measure of the probability that a particle/bubble aggregate pair will become unstable and split to yield a "new" free ink particle. The solution to the kinetic model is presented in terms of k 1 and k 2 , which are themselves functions of system parameters such as bubble and particle physical properties (e.g., diameter, density) and fluid properties (e.g., viscosity, surface tension). From this solution, a definition of theoretical flotation efficiency is presented, as well as definitions of other system performance parameters, and selected predictions are displayed.

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