An injector for injecting particulate material into a metallurgical furnace has a first tubular barrel and a housing defining a chamber having an inlet for particulate material, a first gas inlet and a particulate material/gas outlet connected to the rear end of the first barrel. The first air inlet has a first nozzle operable to inject gas into the chamber at a supersonic velocity when gas at suitable pressure is passed through the nozzle. A second tubular barrel surrounds the first barrel in spaced relationship therewith. The second barrel has a second gas inlet adjacent its rear end and a second nozzle adjacent its front end. Gas under pressure supplied to the second gas inlet passes between the barrels and is discharged at supersonic velocity from the front end thereof adjacent gas and entrained particulate material discharged from the first barrel so as to shroud the particulate material.