Activators

Froth flotation is a process of concentration which separates materials based on their association with water and density. It is mostly used to separate the desired mineral component from a gangue.  It has other applications in the practical field such as, separating plastics, sewage water treatments, and recycling paper. The process requires several reagents to perform efficiently. Activators are one of the important reagents used in froth floatation.

Froth flotation

Froth flotation is a process of concentration that selectively separates minerals based on their relation with water and their density. It is widely accepted over other separation methods like magnetic and gravity separation. The froth flotation method depends on the flotation reagents, not on the properties of minerals.

Froth flotation process

Ore is treated through processes like roughing, cleaning, and scavenging to obtain the most concentrated form of the desired mineral without impurities.

• By a process called liberation, an ore is separated into various minerals.
• Conditioning provides a hydrophobic environment for desired minerals using chemicals or surfactants.
• A sludge of minerals is mixed with water and the frother is added to the flotation column. This step is known as flotation.
• Eventually, frothing occurs with the incorporation of air and only the desired minerals or metals levitate to the surface with air bubbles.
• Separate the froth with a maximum concentration of the desired mineral.

List of chemicals used

The process of froth flotation uses various reagents. Most of them are liquid. If the frother is dry, it must be added in the same form. One pound of the reagent is used for one ton of ore per minute.

• Collectors

It is vital to make the desired mineral hydrophobic in order to separate it from water. Collectors act as the base to make minerals hydrophobic. They increase their floating capacity making them easy to separate.

Examples: xanthates, thiourea thiocarbanilide, and fatty acid.

• Activators 

As the name suggests, activators encourage the binding between the collector and desired mineral.

Example: copper sulphate

• Frothers

Frothers are foam creating reagents, which produce a small air bubble to which the desired mineral is attached. Frothers reduce the surface tension of water.

Example: pine oil, cresylic acid and poly glycol.

• Modifiers

The mineral and collector must interact for the process of froth flotation to occur. Modifiers change the characteristics of a mineral and compelling it to attach with the collector.

Example: lime and soda ash (pH modifier), phosphates and silicates (anionic modifier), starch and dextrin (cationic modifier).

• Depressants: 

These are the reagents used to depress the flotation of certain minerals other than the desired one. Hence they act as inhibitors.

Example: dichromate, sodium cyanide. 

Activators 

An activator is kind of a catalyst which promotes the collector molecule and desired mineral to bind. It helps one mineral levitate in preference to another. Activators are easily ionisable salts.

Activators examples

Copper sulphate and sodium sulphide are the two common activators used in the froth floatation process.

Copper sulphate is used for sphalerite, which is also known as zinc sulphide since its presence increases the air bubble-mineral interaction, enhancing the hydrophobic nature. Froth stability largely affects the process. When the froth is not stable, the bubble layer breaks and most of the desired minerals are drawn back to the slurry.  If the froth is too stable, it will cause the incorporation of gangue into the desired mineral concentration. The only way to survive this is by increasing the hydrophobic nature of the mineral. Copper sulphate is a reagent, which can change the properties of minerals. Hence adding copper sulphate or sodium sulphide as activators make the process much easier without the problems of the froth phase.

Conclusion

Froth flotation is a process of concentration that selectively separates minerals based on their relation with water and their density. It is widely accepted over other separation methods like magnetic separation and gravity separation.