In accordance with the method and the device according to the invention, previous pure pyrotechnic primers for initiating the ignition charges (6a, 6b) of the oxygen lance igniters (13) are replaced by a small quantity of powdered zirconium (7). Zirconium is pyrophoric and therefore ignites, providing it has a sufficiently large surface area, in the presence of a sufficient quantity of pure oxygen, although in ordinary air it is no more flammable than ordinary wood.