A submerged burner for a glass- or rock-melting furnace, including a plurality of in-line injectors, each injector including a cylinder-shaped mixing chamber, with an ejection orifice, a fuel-supply duct and an oxidant-supply duct opening into the mixing chamber at the cylinder jacket in a direction causing a tangential flow of the fuel and of the oxidant relative to the cylinder jacket, and a duct system making it possible for a coolant to flow inside the burner, and, preferably on either side of the alignment of injectors, placed parallel to and all along the latter, solid metal sides rising from the injectors, and protective partitions situated on the top of the solid metal sides.