Advantages and Disadvantages of Froth Flotation

Froth flotation is a concentration process for separating materials based on their association with water and density. It is used mainly to separate the desired mineral component from a gangue. Physical-chemical properties of various flotation chemicals are different. These chemicals are the ones deciding which mineral is getting separated. It has wide application in the practical field. Some of the uses of froth floatation include separating minerals and plastics, sewage water treatments, and recycling paper. Froth flotation has advantages like mineral processing and the highest separation capacity. It also has disadvantages like high cost and maintenance. 

Froth flotation

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

A froth flotation column will have different measurements according to the use. An industrial column will have a height of 6-14 metres and a 0.5-5 metre diameter. If the column is constructed for large-scale production, its diameter will be 4- 4.5 metres, and its height can be up to 12-metre. The column is water washable, and the washing water is poured through a pan having 4-8 mm diameter perforated holes. This is situated 20-30 cm above the froth. 

Have you ever thought about the importance of water washing? It is done to avoid the rebinding of hydrophilic gangue material, which we are trying to remove from the desired mineral. 

Retention time is the time for a mineral to spend in the column. The height of the column is determined by retention time.

Advantages of froth flotation

Froth flotation is a mineral processing method where solid minerals get separated from a mineral pulp based on their surface chemistry. It is always necessary to understand the advantages and disadvantages of froth flotation before choosing, even though 3/4th of the ores in the world use froth flotation as a method of separation.

• High separation efficiency

The separation efficiency of froth flotation is superior. We can understand this by comparing the froth flotation method with gravity separation and magnetic separation methods. Let’s take ‘a’ and ‘b’ as two fine sized minerals with minimal difference in their magnetic property. When these two minerals are separated with the magnetic separation method, they may not get separated due to their almost the same magnetic properties. Since they are fine-sized particles with little density, they cannot be separated with gravity separation either.

But froth flotation is performed by combining physical and chemical properties of minerals- especially surface chemistry of minerals. With appropriate flotation regents, fine particles of minerals separate perfectly.

• Wide application

There are various separation methods nowadays, like gravity separation and magnetic separation methods. But all these methods use the mineral’s nature – magnetic property or difference in specific gravity. But froth flotation is separating minerals with appropriate flotation reagents. With the change in the reagents, the separated minerals also change. In simpler words, froth flotation is never affected by the nature of minerals.

• High efficiency of minerals recovery

When using separation methods other than froth flotation, there is a high chance of obtaining middlings and tailings. They are processed minerals that cannot accept or reject. They might have a considerable amount of gangue with core minerals. These types of substances are known as middlings or tailings. The gravity separation methods and magnetic separation methods produce middlings or tailings most of the time. Froth flotation can selectively separate core minerals from middlings or tailings, making them high-grade mineral concentrate. 

Since froth flotation can separate minerals from already processed concentrates besides the primary ore, it is considered to have high efficiency in recovering minerals.

• Froth flotation is not dependent on the nature of the ore.

Other separation methods like magnetic separation and gravity separation depend on the physical or chemical properties of the ore. However, froth flotation depends on the flotation reagents used.

Disadvantages of froth flotation method

Although froth flotation has several advantages and practicability, the process also carries clear disadvantages.

• High reagent consumption

Flotation reagents are required for the froth. The froth with minerals is collected for separation. Therefore a high amount of reagent consumption is inevitable.

• High cost

Unlike other separation methods, froth flotation requires high maintenance and cost. The pH of pulp, fine grinding of minerals, and temperature of pulp are some matters of importance. If one factor is affected, it affects the overall result.

• Strict grinding size

 The ground size of minerals affects the froth flotation process.

• Environmental pollution 

The flotation reagents, activators, and other chemicals released into the environment cause pollution.

• Numerous factors to consider

There are a lot of factors to consider, such as the temperature and pH of the pulp, flotation time, reagent system, and water quality.

Conclusion

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

The froth flotation method depends on the flotation reagents, not on the properties of minerals.