Introduction

The function of a flotation column is selectively to separate certain suspended solid particles or liquid droplets based on their surface properties. Bubbles rise and particles (drops) settle within the vessel, and collisions are highly dependent on gravitational momentum. The vessel is a multiphase contacting/heterocoagulation device where the dispersed phase to be removed attaches to the bubbles and accumulates at the top of the column in the form of froth. The latter overflows to launders. In this quiescent system, transport, dispersion and mixing of materials are induced by the motion of gas bubbles in the continuous liquid medium.

For the purpose of designing columns, immiscible liquid droplets are considered as acting as solid spheres of an appropriate size and density: thus, a 'particle' may represent either a solid or a liquid.

Almost all flotation columns are operated in the countercurrent regime where slurry moves downwards against a continuous rising bubble swarm. This type of flow increases efficiency (selectivity) of separation as the distance between discharge ports for overflow and underflow is large. In some cases, for example for the flotation of very coarse particles, co-current columns can be considered in order to increase particle residence time and reduce loaded bubble rise time. Unless otherwise stated, all of this article is related to countercurrent columns.

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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