In a process for producing sponge iron from particulate iron oxide-containing material, iron oxide-containing material is reduced to sponge iron with a reducing gas in a reduction zone (4) and gas produced during reduction is withdrawn as top gas. In order to effectively use top gas produced during ore reduction, the CO2 contained in the top gas is removed, the thus obtained CO2-containing waste gas is mixed with an oxygen-containing waste gas is mixed with an oxygen-containing gas, is burned and the thermal energy thus produced is supplied to a consumer.