Concentrate methods:
The most important processes are
- Gravity concentration
- Flotation
- Magnetic and electrostatic separation
Gravity separation separates the minerals according to their different densities. It is used for the concentration of very heavy or very light minerals within a wide range of grain sizes.
In heavy media separation the density of pulp is intermediate between that of valuable mineral and gangue minerals. In that case light minerals float on top and the heavy minerals sink to the bottom of the pulp independent of particle size.
Other methods of gravity concentration utilize a combination of gravitational, inertial, frictional and viscous effects. Commonly used methods are jigging, washing tables, spirals etc.
Separation by flotation is based on the ability or lack of ability of different surfaces to be wetted by water. Hydrophobic minerals will cling to the air bubbles and rise with them, whereas the hydrophilic minerals will sink. Reagents like frothers, collectors, activators, depressors and conditioners are added to make the separation. Floatation has found its greatest application in the concentration of the sulphide minerals.
Electro statics and magnetic separation is based on differences in electrical conductivity of the mineral and magnetic properties the minerals respectively.
Conclusions
In this lecture basic of minerals processing is discussed in brief with the objective to perform materials balance is processing of minerals. Details of the technologies are given in brief and the readers can see the references.
References
A.F.Taggart : Elements of ore dressing
Rosenquist : Principles of extractive metallurgy
Newton .J : Extractive metallurgy.
Kelly and spottiswood: Introduction to mineral processing
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