The size of bubbles in froth is one of the important apparent characteristics of flotation. In the production process, flotation operators can obtain satisfactory mineralized froth by adjusting and selecting appropriate bubble sizes based on experience. The size of froth bubbles varies depending on the ore and the flotation operation. In the flotation of general sulfide ores, bubbles with a diameter of 8–10 cm or more can be considered large bubbles, bubbles with a diameter of 3–8 cm can be considered medium bubbles, and bubbles with a diameter of 1–2 cm or less can be considered small bubbles.
The size of the bubbles is related to the degree of mineralization. When bubble mineralization is good, the bubbles are of medium size; therefore, medium-sized bubbles are commonly seen in the roughing and cleaning zones. When bubble mineralization is poor, they easily merge into large bubbles. Excessive bubble mineralization hinders the merging of mineralized bubbles, resulting in abnormally small bubbles. When bubble mineralization is extremely poor, although small bubbles continuously merge to form large bubbles, they are easily destroyed by disruptive factors such as pulp surface fluctuations; therefore, small bubbles are commonly seen at the tail end of scavenging.
Flotation reagents are the main factor in adjusting froth bubble size. Generally, the larger the amount of frother, the smaller the bubbles; the larger the amount of lime, the larger the bubbles; and the larger the amount of depressant, the smaller the bubbles.