Abstract: An elutriation apparatus for the purification and separation of powders of different densities includes several separating columns each provided at the lower part with a collector for grains receiving the fraction of powder of coarse granulometry and a device for the removal of the grains, and at the higher part a mechanism for the introduction of the powder and of the carrier or transporting fluid and an outlet for the carrier fluid and lighter fractions of the powder. The mechanisms for the introduction of the powder and of the carrier fluid includes at least one distributor tube disposed on the vertical axis of the column and descending within the latter approximately down to the powder collector. The base of the distributor tube has at least one opening discharging towards a deflector. Each column includes of two zones of different sections and the ratio of the sections is constant from one column to the other.