Process and a system for the production of sponge iron from iron ore

A system for the production of sponge iron, the system comprising:

• a direct reduction shaft comprising
• a first inlet for introduction of iron ore into the shaft;
• a first outlet for removing sponge iron from the shaft;
• a second inlet for introduction of a reduction gas into the shaft, and
• a second outlet for removing top gas from the shaft;
• a reduction gas source connected through a first gas line with the reduction gas inlet;
• a reduction gas container;
• a primary circuit for conducting at least a part of the top gas therethrough, said primary circuit being connected in one end with the second outlet and in another end with said first gas line;
• a secondary circuit for conducting at least a portion of gas removed from gas conducted through the primary circuit, said secondary circuit being connected in one end to the primary circuit and in another end to the reduction gas container;
• a second gas line connecting the reduction gas source with the reduction gas container;
• a third gas line connecting the reduction gas container with the first gas line;
• and
• a control unit configured to control a flow of reduction gas from the reduction gas source to the first gas line and to control a flow of reduction gas from the reduction gas container to the first gas line through the third gas line, wherein the control unit is configured to enable a flow of reduction gas from the reduction gas container to said first gas line while correspondingly reducing a flow rate of reduction gas from the reduction gas source to said first gas line.