US Patent 7396503 Lance for injecting particulate material into liquid metal

A metallurgical lance for injecting particulate material into a liquid comprises a main gas tube 6 defining an axial main gas passage terminating at its outlet and in a first Laval nozzle 38 downstream of the throat of said nozzle. A shrouding gas passage in the form of a combustion chamber 36 surrounds the main gas tube and terminates in a second Laval nozzle 42. A particulate material transport tube 4 defines a passage for the particulate material to be introduced into the first Laval nozzle 38 downstream of its throat. The first Laval nozzle 38 is provided with a passage 40 for the flow of coolant.