a shaft reduction furnace is provided with a pressure equalizing chamber for supplying raw materials such as ores in the furnace . the interior of the furnace is separated by a dividing plate into an upper portion and a lower portion . a pipe path through the dividing plate communicates the upper portion with lower portion . the upper portion and the pipe path form an inside ore hopper for supplying ore continuously into the lower portion of the furnace , thus omitting the conventional ore hopper of pressure - proof - structure provided separately outside of the furnace .