Flotation derived from the word meaning float. Flotation can be interpreted as a separation of a substance from other substances in a liquid or a solution based on differences in surface properties of the substance to be separated, where the substances that remain hydrophilic aqueous phase while hydrophobic substances that are air bubbles will be bound by and will be brought to the surface solution and form bubbles which can then be separated from the liquid, where flotation process of gold aims to separate and produce a metal concentrate.

This flotation process produces metals from ore concentrates at the mine by separating valuable minerals from impurities that cover it. This flotation process is said to have been discovered by a miner who see the process of washing machine that is used as a means of washing the dirty work clothes, and the washers that generate bubbles in the foam.William Haynes in 1869 patented a process for separating sulfide and gangue minerals using oil and called it bulk-oil flotation. Flotation process was first commercialized in 1896 in copper mining in Llanelltyd Glasdir near Dolgellau in North Wales with sulphide mineral flotation processes conducted by Frank Elmore and his brother Stanley, and he is the developer of the copper mines.
The main steps performed prior to the flotation process or froth flotation process is the crushing of rock minerals, grinding ore to a size change the amount of fine sand grains in order to liberate the metal to the separation process and to prepare the appropriate size to the next process. Flotation process or froth flotation process consists of mineral concentrates produced through the use of Reagent Flotation, chemical conditioning agents followed by intense agitation and Air Sparging of agitated ore slurry to produce mineral-rich foam concentrate. 

Air bubbles are formed due to air that is inhaled into the pulp, and frother that form the surface free energy at the interface of water and air. To assist in the flotation process, mineral particles must be sized smooth feed. This is because although density large, fine particle size which will cause the association of particle-bubble density becomes smaller than the density of water.Because ion-coated surfaces through physical adsorption or reaction with the ionic chemical collector and change the nature of the organic parts such as a hydrophobic surface. By the nature of the particles become adhesive to air bubbles, so that air bubbles will experience aeration. 

Mineral particles that attach to the surface of the bubbles will be moving up to the surface of the pulp, and indivisible. The particle and bubble need to bind and this occurs if the time in which the particle and bubble are in contact with each other is larger than the required induction time. This induction time is effected by the fluid viscosity, particle and bubble size and the forces between the particle and bubbles.  Flotation on the gold metal is very effective if the gold contained in sulfide minerals such as phyrite, other than that this process is often done if the gold ore minerals join copper, zinc or lead. Flotation process is generally not free floating particles of gold but very effective if the gold is associated with sulfide minerals such as pyrite. In a typical pyritic gold ore, gold formulated in a crystal structure of iron sulfide. Highly oxidized ores generally do not respond well to flotation.

Variables Affecting The Flotation Process Or Froth Flotation Process Are:

1.   State And Grain Size
Mineral grain size that will affect the mineral particles will be greater than the density of water, whereas if it is too small will cause slime that will disturb the flotation process. 

2.   Pulp Preparation The Froth Flotation Process
The provision sought to be suitable for pulp processing that is generally associated with the corresponding percent solid.
3.   The Intensity Of Stirring And The Provision Of Air 
Carried out with stirring in a flotation flotation machines.

4.   Pulp Viscosity 
For a more viscous pulp suspension to be obtained a better recovery.
5.   The Contact Time And Time Flotation 
The increase in recovery occurs at a particular time, which depends on:

     Mineral composition of ore
     The state of the ore particles
     The number of collectors who added
     long stirring
     The size of the ease of a mineral float (float ability)
     grain size

6.   Influence Of pH 
The purpose of pH regulation is to lower the contact angle.
7.   Effect Of Collector
That must be considered is the nature of the collector to be used, for example Xanthate, very good for changing the surface properties of sulfide minerals and coal, easily soluble in water and will not cause frother.

8.   Effect Of Frother 
      Used to stabilize air bubbles for a relatively long time. Percentage of solid 10% is quite good because it can create a quiet zone under a layer of foam which is usually between 10-15% solid. Thus the unwanted particles will drop to the bottom of the cell. Solid percentage is determined by grain size. In the experiment the percentage of 10% solid is not constant due to the addition of water to limit the water that can pass through the layer of froth flotation cell lip. The temperature of the experiment may affect the recovery (yield). A rise in temperature above 40 C causes the air bubbles easily formed due to surface tension decreases.  

The experiments were performed at room temperature between 25-40 C, is still within normal limits and sufficiently qualified for flotation. Impeller rotational speed between 1000-1200 rpm is sufficient to create the conditions for mixing and spread evenly throughout the cell flotation reagents. Rounds that are too high can cause air bubbles to break easily so it will decrease the efficiency of the tool. If too low will extend the time of conditioning. From the data group shown symptoms of the disorder (theoretical) relationship between the yield on the time of flotation. The trend is the increased yield at the beginning of the experiment until a maximum point and turned down.

The advantages of the flotation process, among others;
  • Almost all minerals can be separated by flotation process. 
  • Surface properties can be controlled and altered by flotation reagent. 
  • Very suitable for the separation of sulfide minerals.
The disadvantage of flotation processes include;
  • It costs used in the flotation process is very expensive 
  • The method used in processing complicated, because it must float 
  • Influenced by the slime

Read Also :
- Flotation Cell For Mineral Separation ( Video )
- Froth Flotation Process Of Copper Ore ( Video )

Top Ad 728x90