Abstract: The invention relates to a flotation machine used for separating valuable ingredients, such as metal concentrates, from the rest of the material, which flotation machine comprises at least means for feeding slurry to be treated in the flotation cell into said flotation cell, means for agitating the slurry by a rotor which is to be rotated by a rotation device installed in the vertical direction of the flotation cell underneath the rotor, means for feeding air into the slurry, means for removing the material flotated in the flotation cell and means for removing material that is left non-flotated in the flotation cell. According to the invention the shaft (11, 28) of the rotor (10, 26) meant for agitating the slurry (3, 23) and for feeding air into the slurry (3, 23) and of the rotation device (12, 27) is sealed in the flotation cell (1, 21) by a mechanical sealing member (15).

Abstract: The invention relates to a method and an apparatus for angle measurement or for the determination of an angle of position for an object. The method comprises the use of a beacon having a known position and rotating around its axis, which emits light or reflects light focused thereon. The light emitting from the beacon being determined either previously or for the start of each measurement for a given reference bearing. In the method, the light emitted from the beacon is picked up by a receiver present in an object to be measured, which is provided with elements for determining, by means of the light received from the beacon, the rotational speed of the beacon and further an angular position for the object with respect to said reference bearing.