Abstract: An improved blast furnace for heating granular materials is provided of the "CCR" type which includes two similar stacks disposed side by side, one of which heats the goods by direct current while the discharging gases escape from the other parallel unheated stack in a countercurrent manner. Both of the stacks are provided with an annular channel between the heating and cooling zones thereof which is formed by hollow generally cylindrical members which are connected with each other by cross-intersecting channels. These cylinders are suspended in the enlarged bosh-like lower ends of the stacks by supports which do not extend below the cylinder members, so as to minimize damage to the supports.