Froth Zone

This zone is usually present in solid-solid or solid-liquid separations.

The froth zone in a column cell is characterized by a rising bed containing a matrix of bubbles, which are loaded with hydrophobic material, water lamellae between bubbles and Plateau-Gibbs canals. Entrained hydrophilic material may be found initially either in lamellae or in canals. Film (lamella) thinning and bubble coalescence in froth (syneresis) and drainage in Plateau-Gibbs canals are the main mechanisms of gas hold-up increase and concentrate upgrading with height in the froth. This is caused by reduction of the air-liquid interface area and subsequent particle detachment. Tracer tests indicate that, in some cases, more upgrading is observed within the froth than between slurry and lower froth layers.

Quiescent conditions in columns create a stable froth that allows the addition of wash water. This water displaces the liquid phase of the feed slurry, with entrained associated fine particles, from the froth lamellae and Plateau-Gibbs canals and allows the production of an essentially entrainment-free overflow. In some cases, addition of small amounts of water into the froth also improves the stability and rheological properties of the countercurrent froth.

A presence of highly hydrophobic, angular particles large enough to bridge the lamella between bubbles, without a population of smaller hydrophilic particles, causes froth destabilization. In this case the froth zone design is critical. In extreme cases a froth bed may not be 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.

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