The aim of the invention is to provide a method which optimizes the reduction process at a given ore quality. The reducing gas (7) is analyzed by the gas sensor (1) and divided into two split streams. The mass flow of the split stream to be oxidized is controlled by means of the control valve (3) and then reaches the burner (4) where oxidation takes place. The other reducing gas (7) split stream is controlled at the shaft by means of the control valve (2) in line with the quantity of gas required, raised to the required temperature in the heat exchanger (11) and combined with the oxidized split stream of reducing gas. The gas components are determined by means of the gas sensor (13) and, if necessary, the gas supply (14) is defined on the basis of mathematical formulae. The invention makes it possible to guide the reduction process towards its stoichiometric optimum at a given ore quality. A further advantage is that the reducing gas can be heated to the desired temperature with a very low oxidant component, so that the gas analysis can be adjusted in wide ranges.