Patent ID: 8309016

Claim:
A method for operating a shaft furnace, the method comprising: charging an upper region of the shaft furnace with raw materials, wherein the raw materials sink in the shaft furnace under the influence of gravity and a part of the raw materials is smelted and/or at least partially reduced under the effect of the atmosphere prevailing within the shaft furnace; admitting a treatment gas into a lower region of the shaft furnace via at least one lower admission opening, wherein admission of the treatment gas influences the atmosphere prevailing within the shaft furnace; and modulating the admission of the treatment gas, wherein modulating admission of the treatment gas comprises varying the treatment gas pressure and/or treatment gas volumetric flow over a span of time of less than or equal to 40 seconds; the method further comprising performing an operation selected from the group consisting of (a), (b), and (c): (a) admitting an addition gas via at least one addition opening spaced from the lower admission opening, wherein the addition gas pressure and/or addition gas volumetric flow are varied such that the treatment gas pressure and/or the treatment gas volumetric flow in the interior of the shaft furnace are increased; (b) discharging a shaft furnace gas via a shaft furnace gas line thereby providing discharge of gaseous reaction products from the interior of the shaft furnace, wherein the discharge gas pressure and/or discharge gas volumetric flow of the shaft furnace gas are varied such that the treatment gas pressure and/or the treatment gas volumetric flow in the interior of the shaft furnace are increased; (c) (a) and (b).