Abstract: A shaft furnace comprises a body (2) made up of superimposed heated sections (3,4,5,6 and 7) each of which is provided with a tubular member (10,11,12,13 and 14) having its walls arranged at an angle of 3 to 4 deg. to the longitudinal axis of the furnace. The tubular members (10,11,12,13 and 14) are partially inserted one into another with a gap (15) formed therebetween; the opening area of the lower portion (16) of each tubular member (10-14) of each section (3-7) is 20 to 25 percent smaller than that of the upper portion (17) of the adjacent underlying tubular member (11) of the furnace section (4).In the area of the gaps (15), the upper portions of the tubular members are formed with pockets (30) which are connected with outlet pipes (20) intended for discharging gaseous and vaporous fumes from the furnace shaft.