Procedure and apparatus for separating heavy particles of material from lighter ones

#1. Field of the Invention

#The present invention relates to a procedure as defined in the preamble of claim 1 for separating heavy particles of material from lighter ones, e.g. in mineral separation technology or for separating impurities from powdery or fragmental material, such as chip or fiber material. The invention also relates to an apparatus as defined in claim 6.

#2. Background Art

#In the following, the invention is described by referring to the attached drawings which are given by way of illustration only, and thus are not limitative of the present invention, and, in which:

#FIG. 1 presents an apparatus of the invention in simplified side view,

#FIG. 2 presents another embodiment of the apparatus of the invention in simplified side view, and

#The apparatus of the invention comprises a carrier surface 1 pervious to gas, onto which the material to be treated is supplied. The motion of the carrier surface 1 is mainly a movement in one direction, and it may be continuous or intermittent. The carrier surface may also move through a certain distance and then return to its initial position. The carrier surface 1 is preferably an endless belt which is moved in the direction indicated by the arrows. Disposed below the carrier 1 are means 3, 4 for producing gas impacts P and applying them through the carrier surface 1 to the material flow. The means for producing gas impacts P comprise a chamber 3 disposed under the carrier surface 1, into which chamber gas is supplied and whose wall opposite to the carrier 1 is provided with at least one aperture, and at least one valve element 4 for regulating and/or closing the gas flow passing through the aperture/apertures, by means of which the gas impacts are thus produced.

#According to the procedure of the invention, material 2 to be sorted is brought onto the carrier surface 1 pervious to gas and gas impacts P are applied to the material through the carrier surface 1, causing heavier particles to move into the area closest to the carrier surface. The carrier is mainly moved in one direction to move the heavy particles R, while the lighter particles K are passed on, mainly by the agency of the inclination of the carrier 1 and/or the gas flow, in a direction substantially differing from the principal direction of movement of the carrier 1.

#The embodiment illustrated by FIG. 1 uses a guiding element 7, such as a wall 7, placed at an optional angle above the carrier surface to direct the gas flow of the gas impacts P in the space between the wall 7 and the carrier surface 1. The wall enables the gas of the gas impacts to be used to convey the lightest particles K, such as chips and fibres. In this figure, the wall 7 directs the gas flow to the left as indicated by the arrows.