Abstract: A lance for blowing an oxydizing gas onto a bath of molten metal, especially for blowing oxygen on a bath of molten pig iron for transforming the same into steel. The lance is provided in an end wall of its nose with at least one central aperture for blowing gas jets at great impulsion onto the bath and a plurality of auxiliary apertures for blowing gas streams of considerably smaller impulsion onto the bath. The auxiliary apertures are constituted by elongated slots through the end wall arranged spaced from each other along a circle at a distance of adjacent edges of the slots and that at least one main aperture of about 2-20 cm. This construction permits to improve the amount of secondary combustion of the reaction gas while prolonging the useful life of the nose of the lance. The lance is advantageously used in conjunction with blowing a stirring gas through the bath of molten metal through refractory gas permeable elements provided in the bottom of a crucible containing the bath.