Flotation method for removing impurities from aqueous fiber suspension in flotation container, involves collecting impurities of aqueous fiber suspension in flotation froth, and discharging impurities with flotation froth

摘要

The method involves feeding a flow (8) of gas into a mixing device with a flow channel (6) through a flow (10) of aqueous fiber suspension, and forming a gas bubble. Impurities of the fiber suspension are collected in a flotation froth and are discharged with the flotation froth. A circular flow cross section of the flow channel in a flow direction continuously changes within a maximum of 20 mm, where a circumference of the cross section of the flow channel is uneven in different directions. A cross section surface of the flow channel in the flow direction is enlarged.