Patent ID: 7597739

Claim:
A process for reducing iron ore-containing particulate material in an at least two-stage process performed in an apparatus comprising a plurality of reaction zones arranged consecutively in series and formed by a moving particulate material, the process comprising: conducting a reducing gas not containing O 2 through at least a first one of the reaction zones in a gas pathway and then through a second one of the reaction zones in the gas pathway consecutively in the series, the reaction zones in the gas pathway being gas pathway reaction zones; moving particulate material consecutively through the series of reaction zones in the reverse sequence to the sequence of the conduction of reducing gas through the series of reaction zones, through a first one of reaction zones in a particulate pathway and then through a second one of the reaction zones in the particulate pathway, the reaction zones in the particulate pathway being particulate pathway reaction zones; heating the particulate material in the first particulate pathway reaction zone and reducing the particulate material in each of the further particulate pathway reaction zones consecutively in the series by the reducing gas that is being conducted through the reaction zones; adding reducing gas to the first particulate pathway reaction zone and conditioning the reducing gas added to the first particulate pathway reaction zone so that oxygen bound to the iron ore is removed at a maximum reduction speed of 0.2% oxygen removal per minute, wherein the reducing gas added to the first particulate pathway reaction zone is conditioned by at least one selected from increasing the degree of oxidation of the reducing gas, and decreasing the temperature of the reducing gas, or both carried out jointly, so that a range of no reduction to hardly any reduction occurs in the first particulate pathway reaction zone, the preheating of the particulate material being sufficient for causing a preheating temperature of the particulate material within the fringe range of starting of reduction, and removing oxygen bound to the iron ore at a maximum maintained reduction speed of 0.2% oxygen removal per minute in the first particulate pathway reaction zone, adjusting the temperature level in the first particulate pathway reaction zone to be between 350° and 550° C., and maintaining an average retention time for the particulate material in the first particulate pathway reaction zone of up to forty minutes, wherein the temperature level in the second particulate pathway reaction zone is at least 600° C.