One of the most important skills in flotation operation is observing froth and judging the quality of flotation based on its changes.

The ability of a flotation operator to correctly adjust the amount of flotation reagents, concentrate scraping, and middlings recycling depends primarily on their accuracy in judging the appearance of the froth. The appearance of froth includes its density, size, color, luster, shape, thickness, intensity, fluidity, and sound. These phenomena are mainly determined by the type, quantity, particle size, color, luster, density, and amount of frother adhering to the froth surface.

The appearance of froth varies depending on the flotation zone, but specific zones often exhibit specific phenomena. When observing froth, focus on several cells with distinct characteristics that have a major impact on concentrate quality and recovery rate. These include the final concentrate output cell, the first few cells in operation, the reagent addition cells, and the scavenging tail end cells.