Abstract: A process for discharging a reactor characterized by reducing the volume of a powder without compacting it, including treating the powder in a densification zone including at least one Archimedes' screw arranged in a barrel. The Archimedes' screw may also have both a reduction in pitch and an increase in diameter of the shaft. The densification zone may also contain two co- or counterrotating screws arranged in a barrel and exhibiting a reduction in the pitch of the screws. Densification zones consisting of two co-rotating screws give particularly good results.