A smelting process used to extract lead from ores. It involves feeding pellets of lead sulphide ore concentrate into a bath of molten slag in a rotating cylindrical furnace. By feeding oxygen below the slag on the surface, sulphur dioxide is formed along with heat. The lead oxide is reduced to metal by the addition of powdered coal. The process is named after its inventors P. E. Queneau, R. Schumann, and is now operated by Lurgi GmbH.