Apparatus for dry granular mixtures separation

An apparatus for separating dry granular mixture of particles of different densities into a first fraction and a second fraction, the first fraction having particles of higher density than the second fraction, the apparatus comprising:

• a channel spiraled about an apparatus axis of rotation into a plurality of turns successively arranged from a front apparatus end to a rear apparatus end, the apparatus axis of rotation extending longitudinally from the front apparatus end to the rear apparatus end, the channel configured to rotate about the apparatus axis of rotation, each of the plurality of turns having
• a granular mixture retention volume having an open radial inner side that faces toward the apparatus axis of rotation, the open radial inner side of the granular mixture retention volume of each turn from the front apparatus end to the rear apparatus end being successively closer to the apparatus axis of rotation,
• wherein, when the apparatus is rotated about the apparatus axis of rotation and a granular mixture of particles of different densities is introduced into the channel, the apparatus causes spatial separation of the granular mixture within the granular mixture retention volume of each turn of the channel into the first fraction and the second fraction by producing continuous or discrete avalanches in a surface of the granular mixture whereby, within the granular mixture retention volume of each turn, the first fraction is moved towards a center of a volume of the granular mixture and the second fraction is moved radially outward from the center of the volume of the granular mixture.