Flotation of Solid Particles to Liquid Surface

In only rare cases does one find minerals or metals in pure form (such as gold). The earth s surface consists of a variety of minerals (major components iron, silica oxides, calcium, magnesium, aluminum, chromium, cobalt, and titanium). 

Minerals as found in nature are always mixed together (e.g., zinc sulfide and feldspar minerals). In order to separate zinc sulfide, the mixture is suspended in water, and air bubbles are made to achieve separation. This process is called flotation, where an ore heavier than water is floated by bubbles. 

Flotation is a technical process in which suspended particles are clarified by allowing them to float to the surface of the liquid medium. The material can thus be removed by skimming at the surface. This is economically much cheaper than any other process. If the suspended particles are heavier than the liquid (such as minerals), gas (air, C02, or other suitable gas) bubbles can enhance the flotation. 

FIGURE 5.13 Flotation of mineral particles as aided by air bubbles. 

FIGURE 5.14 Contact angle at a mineral particle and liquid interface. 

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