Apparatus for operating a shaft furnace, whereby an upper section of the shaft furnace is charged with raw materials which due to gravity descend inside the furnace while the atmosphere prevailing within the shaft furnace causes part of the raw materials to melt and/or to be reduced, and in a lower section of the shaft furnace a process gas is injected so as to at least partly modify the atmosphere prevailing in the shaft furnace. The pressure and/or volume flow of the injected process gas is dynamically modulated within a time span of 40 s. Also, a shaft furnace operable by said method, thus achieving improved through-gassing.