FLOAT FLOTATION | Mineral Processing

Float Flotation


Float flotation is a physico chemical process of concentration based on the air and simultaneously adhesion of other particles to water in a pulp. The ore Benification and the facts are :-
1. Most minerals, if suitably protected from contamination, adhere to water but not to air.
2. Paraffins and other hydrogen adhere to air in preference to water.
3. Some minerals adhere to air.
4. Changing the surface conditions if the minerals will affect the float ability.

Natural Flotatbility :

● Hydrocarbon, coal and sulphur shows large degrees of natural floatability.
● It is to be observed that substance showing natural flotability, where the mineral are polar.

Aequired Flotability :

● The surface of one or another a group of mineral with a film that is non polar.
● Galena from sphalerite and sulphide mineral are non polar.

Physio Chemical Principle of Flotation :

1. It is thought that the collectors are adsorbed on the surface of the mineral storming a continuous heterpolar film in the range of molecular levels.
Float flotation process - mineral processing
Float floating principle

* The heteropolarity of the film is such that the non polar part of the film is oriented away from the mineral body.

 * Some mineral particle like a non polar particle, becomes non wettable and attached itself precferentially with a air bubbles.

2. The air bubble mineral combination fluids up in the fluid as per Archimedes principle as long as the combination specific gravity is less than the specific gravity of the fluid.

Floatation Reagents :

For proper froth flotation use of following reagents
Flotation reagents
Reagents
1. Collectors
2. Frothers
3. Modifiers

Collectors :

These reagent from a heteropolar molecular level continues film around the minerals.

● As these films are hydrophobic in nature they repel water and get attached to the air bubbles and ensure the mineral air associated to float up.
● The collectors are broadly classifieds as cationic and anionic.

● Some typical collectors are potassium entyl xanthale or sodium ethyl xanthale, dithiophosphate, fatty acids and fatty amine accurate.

Anionic Collectors :

● If the part which impacts water repellency to the mineral surface carries a negative charge.
● K or Na ethyl xanthales dithiophoshates fatty acids.

Cationic Collectors :

● If this part is positively charged the collector is called cationic.
● Fatty amine accutate.

Frothers :

These reagents produce forth of desired properties on which collector coated mineral get attached and are floated up.

● These are heteropolar organic compound having one or more water repellant.
● These are surface active reagents collect at the air water interface.
● Used frothers are pine oil, aliphatic alcohol and corrsylic acids.

Modifier :

It may necessary to use a modifier before any collector can be made to function effictieffe I.e.

● Utilize collectors under optimum condition.
● control mutual mineral interaction.
● control action of mineral surfaces by atmospheric.
● Adversity the ability of some minerals to acquire floatability.

According to their function the modifying agents may be classed in to one of the following categories :
1. PH requlator
2. Activator
3. Depressant or depressor
4. Dispersant.

PH Regulator :

● In flotation operation maintain in a particular range of PH value of the pulp.
● The reagents commonly used to control PH are lime, soda ash and sulphuric acid.

Activator :

● if a minerals has been depressed or is not floatable an activator is used to reactivate or increase it's susuptibility to flotation.

● Copper sulphate CuSO4 is standard activator for sphalerite. Hydrogen sulphide H2S or sodium sulphide for Galena.

Depressants or Depressor :

It is desirable to prevent the flotation of one mineral over another, for such a separation a class of reagents are added to the pulp called depressant or depressor.

● Which works both as a pH controller and depressant.
● Sodium as anide along with zinc sulphate is a depressant for sphalerite.
● Dichromate salts are used to depress flotation of galena.

Dispersant :

● The gangue may interface with efficient flotation of the desire mineral.
● Then it becomes essential to use a dispersant or deffloculator.
● Sodium silicate is used as a dispersant.

Flotation Technology :

For proper flotation following condition are to be satisfied.
Particle size : The maximum size depending on ore treated, recovery decreasees marked. If the particle are finer than 5 - 10 microns.
Example : coal = 10 to 14 #,   Sulphides = 4 to 65 #,   Gold = 100 to 150 #

Pulp density :  The pulp must be diluted for proper separation. Practically speaking no pulp thicker than 35 to 40% solid can be used.

Conditioning : It is mixing of ore with water and acration prior to separation in a cell.

Temperature : Pulp temperature is maintained between 12 to 20℃.

Reagents : Addition of reagent to the pulp in proper quantity is essential to obtained best result and subsequent maintenance of reagents percentage in the cell.




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