Method of injecting a powder containing carbon into a metal bath

A method of deoxidizing or carburizing a ferrous metal bath by injecting into the bath a carbon powder by means of at least one immersed nozzle consisting of two concentric tubes, the method comprising feeding the central tube of said nozzle successively with pure oxygen during the oxidation phase or phases, then with a scavenging gas, selected from the group consisting of nitrogen, argon and carbon dioxide and then with a neutral gas carrying said carbon powder during the deoxidation or carburization phase or phases, and finally with said scavenging gas before repeating the cycle, while feeding said peripheral tube successively with a fluid protecting said nozzle against wear during the oxidation phase or phases, and with this same fluid or another protective fluid during the deoxidation or carburization phase or phases and wherein the central tube of said nozzle is supplied by two distinct pipes, the first of the two pipes being fed selectively with pure oxygen or with said scavenging gas, the second of the two pipes being fed selectively with said neutral gas carrying the carbon powder or with said scavenging gas and wherein any contact between pure oxygen and carbon powder is avoided.