A charging system for a shaft smelt reduction furnace includes a frame structure for mounting on a top charge opening of a shaft smelt reduction vessel; a center shaft arrangement supported by the frame structure and for removing off-gas gases from the furnace and to introduce granular charge materials to form a stack of materials in the furnace. The center shaft arrangement includes a center hood for off-gas extraction; a pair of first and second feed channels for first and second materials. The center hood includes a pair of facing off-gas panels defining an off-gas channel. The partition walls include lower portions that extend towards each other below the center hood to define a center feed passage, whereby material descending through the first feed channels may accumulate on lower portions according to the angle of repose of the material, permitting self-adjustment of the first material stock-line in the shaft arrangement.