Gas-solid particle-liquid system in mineral flotation

10 Gas-solid particle-liquid system in mineral flotation 

In Section 3.3.8, the principle of particle separation via flotation in a gas-liquid system was briefly identified. Those particles whose surfaces are hydrophobic, and to which gas/air bubbles can be attached, will float to the surface of an aqueous suspension due to reduced density. Those particles whose surfaces are hydrophilic and wetted by the liquid (commonly, it is water) cannot become attached to gas/air bubbles and will not therefore float to the surface. Here, following Fuerstenau and Herrera-Urbina (1989), we will briefly iUusUate systems where such separations are achieved by converting particular mineral surfaces to a hydrophobic type via the adsorption of 

The primary step involves the use of surface-active collectors, which displace water molecules from the surface of the mineral if the mineral surface is charged, appropriate long-chain ionic surfactants, which can act as a counterion to the charged surface, are used. The long hydrophobic chains of such surfactants present a hydro-phobic surface. Surface-active collectors, which are chemisorbed at the mineral-water interface, can also create a hydrophobic surface. An additional approach employs substances called depressants, which inhibit the attachment of gets bubbles to the minerals that should not undergo flotation. 

The key to any approach is knowing the electrical charge and potential on the surface of the mineral particle in an aqueous suspension. The following four phenomena contribute to the development of the surface charge specific adsorption of surface-active ions preferential dissolution of lattice ions dissociative adsorption of water molecules isomorphous substitution of ions comprising the mineral lattice (Fuerstenau and Herrera-Urbina, 1989). 

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