Abstract: This invention relates to the draining of bulk materials which are not spontaneously flowable, from a high-rise silo in which the bulk material is fed from the top layer of the bulk material at any instant, into a central gravity shaft having a bottom extraction facility. To this end, the invention consists in a gravity shaft which is combined with the gastight high-rise silo and is rigid, stationary, tubular and closable at the bottom. The shaft is provided with perforations distributed along its height and circumference, of which at least one is situated at each vertical position of the prevailing level of bulk material. The bottom of the shaft can be sealed off with a slider or a plug of the material which is permitted to be built up to a predetermined height.