A charging system for a shaft smelt reduction furnace, comprising: a frame structure for mounting on a top charge opening of a shaft smelt reduction vessel; a center shaft arrangement supported by said frame structure and configured to remove off-gas gases from the furnace and to introduce granular charge materials in order to form a stack of materials in the furnace, said center shaft arrangement comprising: - a center hood for off-gas extraction; - a pair of first feed channels (36, 36') for a first material, one on each side of said center hood; and - a pair of second feed channels (38, 38') for a second material arranged on respective sides of said first feed channels; wherein said center hood comprises a pair of facing off-gas panels (44, 44') defining an off-gas channel, each off-gas panel cooperating with a respective partition wall (48, 48') to define a respective first feed channel (36, 36'); and wherein each partition wall (48, 48') cooperates with a respective outer wall (50, 50') to define a respective second feed channel (38, 38'); wherein the partition walls (48, 48') comprise lower portions (54, 54') that extend towards each other below said center hood to define a center feed passage, whereby material descending through said first feed channels may, before flowing through said center feed passage, accumulate on said lower portions (54, 54') according to the angle of repose of said material, thereby permitting self-adjustment of the first material stock-line in the shaft arrangement. a frame structure for mounting on a top charge opening of a shaft smelt reduction vessel; a center shaft arrangement supported by said frame structure and configured to remove off-gas gases from the furnace and to introduce granular charge materials in order to form a stack of materials in the furnace, said center shaft arrangement comprising: - a center hood for off-gas extraction; - a pair of first feed channels (36, 36') for a first material, one on each side of said center hood; and - a pair of second feed channels (38, 38') for a second material arranged on respective sides of said first feed channels; - a center hood for off-gas extraction; - a pair of first feed channels (36, 36') for a first material, one on each side of said center hood; and - a pair of second feed channels (38, 38') for a second material arranged on respective sides of said first feed channels; wherein said center hood comprises a pair of facing off-gas panels (44, 44') defining an off-gas channel, each off-gas panel cooperating with a respective partition wall (48, 48') to define a respective first feed channel (36, 36'); and wherein each partition wall (48, 48') cooperates with a respective outer wall (50, 50') to define a respective second feed channel (38, 38'); wherein the partition walls (48, 48') comprise lower portions (54, 54') that extend towards each other below said center hood to define a center feed passage, whereby material descending through said first feed channels may, before flowing through said center feed passage, accumulate on said lower portions (54, 54') according to the angle of repose of said material, thereby permitting self-adjustment of the first material stock-line in the shaft arrangement.