US Patent 9056287 Flotation machine

An air distribution and mixing device is arranged in the vicinity of the bottom of a flotation cell for distributing air to the slurry for forming froth and mixing the slurry in the flotation cell. A rotor part of the air distribution and mixing device has air distribution apertures and is attached to the lower end of a drive shaft extending vertically in the flotation cell. The drive shaft has a hollow interior, which constitutes a flow channel for conducting flotation air to the air distribution holes of the rotor part. An electric motor for rotating the drive shaft is supported by a separate supporting framework, which is on top of the flotation cell. The electric motor is a permanent magnet motor having a vertical rotor shaft, the lower end of which is in permanent contact directly with the upper end of the drive shaft.