Write a short note on forth flotation process associated with the extraction of metals form their ores.
Froth floatation Process:
1. Hydraulic Washing (Gravity Separation)
The ore particles are poured over a hydraulic classifier which is a vibrating sloped table with grooves and a jet of water is allowed to flow over it. The denser ore settle in the grooves while the lighter gangue particles are washed away. This method is used for concentration of heavy oxide ores of lead, tin, iron etc.
2. Froth Floatation
This method employs a mixture of water and pine oil which is made to froth in a tank to separate sulphide ores. The differences in the wetting properties of the ore and gangue particles separate them.
A mixture of water, pine oil, detergent and powdered ore is first taken in a tank. A blast of compressed air is blown through the pipe of a rotating agitator to produce froth. The sulphide ore particles are wetted and coated by pine oil and rise up along with the froth (froth being lighter). The gangue particles wetted by water sink to the bottom of the tank (water being heavier). Sulphide being more electronegative attracts the covalent oil molecules. The gangue being less electronegative is attracted by the water. The froth containing the sulphide ore is transferred to another container, washed, and dried.
3. Magnetic SeparationBack to Top
Magnetic ores like pyrolusite (MnO2) and chromite (FeO.Cr2O3) are enriched by this method by making use of the difference in the magnetic properties of the ore and gangue particles.