Flotation plant operators often use the virtual ( also known as empty ) and real ( also known as knot ) foam as a reflection of the degree of mineralization. The mineral particles attached to the surface of the bubble are dense and dense, which is called “ real ” . The mineral particles attached to the surface of the bubble are few and thin, which is called “ virtual ” . Flotation workers always want to see the mineralized foam in the roughing tank to be “ real ” , and the mineralized foam in the tail trough should be “ virtual ” (the surface has very few useful minerals, which is manifested by the adhesion of only one layer of slime. a more transparent vacuole ) .