Abstract: A rotor for the distribution of air in the form of finely divided bubbles in the slurry in a flotation tank comprises a boss with an inner hollow air passageway, spaced-apart wings extending radially outwardly from the outer surface of the boss, and multiple air conduits communicating between the inner hollow air passageway and the surface of the boss between each adjacent pair of wings. The air conduits have outer mouths located immediately behind a wing (behind in the sense of rotational direction of the rotor) and linearly extend to the inner hollow air passageway such that lines through their central axes will intercept with imaginary radial lines passing through the centers of the wings behind which the outer mouths of the respective air conduits are located.