In the process for discharging solids treated with liquids from vertical columns, the treated solids are transported by means of a conveyor to a circulating auxiliary liquid with variable hydrostatic pressure and from there to the subsequent stage of treatment. By varying the hydrostatic pressure of the cycle of auxiliary liquid, the pressure conditions in the system can be adjusted in a manner to permit discharging from the column pure solid or solid with a defined amount of adhering liquid, or introducing defined amounts of liquid from the auxiliary cycle into the column in countercurrent flow with respect to the direction of flow of the solid.