Wetting of the Particles Surfaces

The particles are always dispersed in water and the nature of the wetting of their surfaces is critical for the effectiveness of the flotation separation.

Figure 1 shows the concept of an attached water film in which water dipoles are held by van der Waals forces together with ions held by electrostatic interaction with charges on the particle surfaces.

The stability of the adsorbed water film on the solid surfaces is clearly fundamental to the selective attachment of bubbles. Qualitatively for hydrophilic particles the water film is strongly bound to the solid, and hence is stable; conversely for hydrophobic solids the water film is weakly bound and will fail more readily.

The attachment of hydrophobic particles to bubbles is usually considered to consist of two sequential stages. First, the particle must collide with (intercept) the bubble. The second stage after interception has two components: (a) a bubble-particle contact time and (b) an induction time which is that required for the water film between the particle and bubble to thin to a point of failure at which point attachment is presumed to occur.

The selectivity of the separation is commonly enhanced by the adsorption of surface active chemicals onto the surfaces of the solid particles. These reagents have a molecular structure which has a polar and

The upper limit, G = 1, clearly follows from the concentrate mass fraction of valuables, xC = 1, while the lower limit, G = 0, presumes that the worst system performance is associated with no upgrading of the valuable mass fraction in the concentrate with respect to its concentration in the feed, although negative grades are mathematically possible.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

Get My Free Ebook


Post a comment