What Is Froth Flotation?

Froth flotation is a method of separating minerals from impurities or from one mineral to another. The unrefined ore powder is stirred with water and reagents, and the reagents preferentially adhere to the target ore to change its surface characteristics. Then air is introduced into the mixture, and the target ore floats with the bubbles to the surface of the mixture to form a foam. After defoaming, the target ore can be obtained. ^[1]

The process of recovering materials from the pulp by flotation includes the following three mechanisms:

(1) Selective adhesion on air bubbles (or true flotation);

(2) Entrainment from water through foam;

(3) Physical trapping (usually referred to as agglomeration) of particles stuck to the bubbles in the foam.

The adhesion of useful minerals to air bubbles is the most important mechanism that determines whether most of the particles can be returned to the concentrate. Although true flotation is the main mechanism for useful mineral recovery, the separation efficiency of useful minerals from gangue minerals also depends on the degree of entrainment and physical capture. True flotation is recovered based on the chemical selectivity of the surface characteristics of the mineral, but both useful minerals and gangue minerals can be recovered through entrainment and physical capture. The removal of floating minerals in the foam layer and the control of the stability of the foam layer are important to obtain a good separation effect. In the practice of industrial flotation plants, the entrainment of gangue is more common, so it is not common to use a single stage flotation operation. In order to achieve the economically acceptable quality of useful minerals in the final product, several stages of flotation are generally required (called "Process").

True flotation takes advantage of the differences in the physical and chemical surface characteristics of different mineral particles. When the surface of the mineral is treated with a medicament, the difference in surface characteristics between the minerals in the flotation pulp is more obvious. In order for the flotation to occur, the bubbles must be able to adhere to the mineral particles and then float the mineral particles to the liquid level. ^[2]

Factors affecting flotation include particle size, pulp concentration, adjustment of pharmaceutical additives, adjustment of bubbles and foam, temperature of pulp, flotation process, water quality, etc.

Factors affecting the flotation rate: the properties of ores and minerals such as the type and composition of minerals, particle size distribution, shape of ore particles, degree of monomer dissociation, mineral surface properties; various factors in flotation chemistry such as the selectivity of collectors, Collection capacity, type and amount of activator, inhibitor, foaming agent, pH of the medium, water quality, etc .; characteristics of the flotation machine such as its structure and performance, aeration volume, bubble size distribution and degree of dispersion, degree of agitation, foam Layer thickness and stability scraping speed; operating factors such as pulp concentration and temperature.