Flotation machine

A flotation machine for floating hydrophobic particles from aqueous slurry that contains these particles, comprising

• a flotation cell that comprises a vertical side wall and a bottom;
• an air distribution and mixing device, which is arranged in the middle part of the cell to distribute air into the slurry for forming froth and mixing the slurry in the flotation cell, the air distribution and mixing device including a rotor part that comprises air distribution apertures;
• a drive shaft, which is arranged so as to extend vertically in the flotation cell, the rotor part being attached to the lower end of the drive shaft, the drive shaft comprising a hollow interior, which constitutes a flow channel for conducting flotation air to the air distribution apertures of the rotor part;
• and
• an electric motor for rotating the drive shaft;
• wherein the electric motor is a permanent magnet motor that comprises a vertical hollow rotor axis, the lower end of which is in a fixed connection directly with the upper end of the drive shaft, and wherein the permanent magnet motor includes a stator which is attached to a framework above the flotation cell, and a rotor, on the periphery of which there are a number of permanent magnets, the rotor being fixedly connected to the vertical rotor axis, the rotor axis fitted with a bearing that rotates with respect to the stator using an upper bearing and a lower bearing together forming the bearing of the drive shaft, which receives loads caused by the air distribution and mixing device.