The stirring of the pulp during flotation can be divided into two stages based on its function: first, stirring before the pulp enters the flotation machine, which accelerates the interaction between mineral particles and reagents; second, stirring after the pulp enters the flotation machine, which suspends the mineral particles, disperses air bubbles, and promotes particle adhesion to the air bubbles.
Strengthening stirring in the conditioning tank can promote the interaction between mineral particles and reagents, shorten the pulp conditioning time, and save reagent usage. The stirring intensity in the conditioning tank depends on the impeller speed; the higher the impeller speed, the greater the stirring intensity.
Appropriately increasing the stirring intensity is beneficial, but it should not be excessive. Excessive stirring increases power consumption and equipment wear, increases the degree of mudding of mineral particles, and can also cause mineral particles already attached to air bubbles to detach.
The stirring time in the mixing tank depends on the ease with which the reagent disperses in water and the speed at which it interacts with the mineral particles. Frothing agents (such as pine oil) only require stirring for 1-2 minutes, while general reagents require 5-15 minutes. Flotation of cassiterite using mixed toluene and secondary acid often requires 30-50 minutes. When using dichromate to suppress galena, the stirring time needs to be more than 30 minutes, sometimes reaching 4-6 hours.
The stirring time also depends on the purpose and properties of the reagent. For example, when using sodium sulfide to sulfide non-ferrous metal oxide ores, the stirring time must be appropriate; too short a time will result in insufficient sulfidation, while too long a time will cause the sodium sulfide to oxidize and become ineffective.