Apparatus required:- Coal(fine size), pine oil (frother), Kerosene(activator).
It is process of rendering a mixture of finely ground minerals susceptible to gravitational separation.
This is done by selective adhesives of air bubbles to the mineral species.
The surface characteristic of a important and used as criteria for separation. The surface properties;
1) Surface tension
2) Surface energy
3) Contact angle
Some particles adhere to air bubble (air water interface) in the pulp, some to water i.e. wetted.
In this process adhesion is effective between air and small mineral particles so that the specific gravity of the minerals air associated conglomerate is less than that of pulp. This makes the conglomerate to rise in the pulp. The floating mineralized forth is then mechanically separated from the pulp.
The cause of the process of floatation is the extensive tendency of the mineral particles to adhere to air & other to water. This is due to the difference in physico chemical surface properties of particles of different minerals.In flotation the concentrate is usually transferred to the froth, leaving the gangue in the pulp (tailing). This is called direct floatation. In indirect floatation, gangue is separated in froth & concentrate sinks at the bottom.
PRINCIPLE: It is a physio- chemical separation process that whiteless the reference in surface properties of the valuable minerals and the unwanted gangue materials. The process of minerals being recovered by flotation from pulp comprises 3 mechanism-
1) Selective attachment of the air bubbles
2) Entraiment in the water which passes through the forth.
3) Physial entrapment between particles in the foloth attached to the air bubbles.
Many chemicals are used in floatation process in order to
1) Modify the surface the surface of the mineral to make the hydrophobic or aero phobic. (Adhesive
2) Make forth more stable.
3) Increase the effect of chemicals (catalyst) used to make minerals hydrophobic.
4) To attain desired condition of PH in the feed pulp. Process:
1. ½ tank water
2. So gm powder fine + pine oil+ Kerosen+ Soapsolh(tank)
3. Stirring for 5 min.
4. Start compressor
5. Collect forth in a sieve (250 mesh)
6. Dry at drier
Collectors are organic compound which when added in small quantity to the pulp absorb selectively on the mineral surface (mineral-water interface) and increase its hydrophobicity so that they can attach to the air bubble. Collectors may be ionizing or non ionizing compounds. Ionizing collector may ionize or dissociate into ions in water. Non-ionizing compounds which are partially insoluble render mineral water repellant by forming a thin film.
Comparison with Gravity Separation:
1. Gravity separation is simple compared to forth flotation which is complex various chemicals are used to change the surface property in flotation.
2. Gravity separation in environmental friendly while forth flotation deals with dust.
3. Gravity separation can be used if the liberation takes place at a coarser size range, while forth flotation is used for fine size range.
4. Gravity separation is economical while forth flotation used expensive chemicals.
Its main function is to produce stable forth in the process and also to maintain the PH of the pulp