By way of example, FIG. 1 of WO2006135984 describes a process for the reduction of metal oxides to form metalized material by contact with hot reducing gas, which is produced by catalytic reformation of a mixture of natural gas with the top gas taken from the reduction unit, wherein the fuel gas for burners which provide the heat for the endothermal reformation processes which take place during the reformation is obtained from a partial quantity of the top gas produced during the reduction of metal oxides to form metalized material and from natural gas. Owing to ever more stringent statutory environmental regulations, it is desirable to separate CO2 in order to produce a concentrated CO2 flow from the off-gases produced during the processes, with the possibility of subsequent sequestration of the CO2 flow, before the off-gases treated in this way are released into the environment. In the case of a process as shown in WO2006135984, the fuel gas for the reformer is combusted with air as the oxygen source, for which reason the combustion off-gas contains a large quantity of nitrogen. Correspondingly, downstream plants for removing CO2 from the combustion off-gas have to have large dimensions. Additionally, substantially only chemical absorption processes are suitable for removing CO2 from the combustion off-gas, and these are distinguished by a large plant size and a high consumption of energy, which is supplied, for example, using steam.