Choice of hydrodynamic regime under production conditions

Appendix IOC Choice of Hydrodynamic Regime under Production Conditions. Decimicrone-Size Particle 

Means of control differ substantially depending on whether attachment forces are large or small, i.e. the potential well is not deep or is absent. The modes of control of particle and bubble charges should be selected already at the stage of studying the properties of the flotation system. It is advisable to conduct experiments of flotation recovery of particles by bubbles of small and large size, for example, at Re 1 and Re 400. Clearly, opposite charges of particle 

A drift of surfactant to the rear zone can appear for large bubbles with a slightly retarded surface so that their selection is restricted by condition (8.71). In that case it is preferable to change the sign of the particle charge in order to decrease reagent consumption. 

If a noticeable recovery is also observed at large bubble size, the potential well is deep, i.e. an a-film is either absent or very thin. 

This barrier can be caused either by the hydrophilicity of the particles, by the availability of a boundary water layer near the particle surface (cf. Section 10.5) or by a surfactant adsorption layer hydrophilising the particle. Since hydrophilicity of many dispersed systems has been studied in colloid chemistry, independent information can be used to identifying the nature of the barrier at the particle surface. Broad experience in flotation of large particles can be used for selecting surfactants to destruct the boundary layer of particles of a concrete nature. 

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