Method of controlling the stirring strength and flow rate of a jet of gas blown through a lance onto a molten metal surface

A method of controlling independently of each other the stirring strength of a jet of oxygen gas and the flow rate of the oxygen gas to be blown onto a molten metal bath in a top-blowing oxygen furnace provided with an oxygen supplying conduit, a means of detecting the temperature of the supplied oxygen gas in said oxygen supplying conduit, a means of detecting the pressure thereof, and a means of heat-exchanging with the supplied oxygen gas, controlling the stirring strength of the jet of oxygen gas and the flow rate of the oxygen gas independently of each other;

• maintaining a lance of the topblowing furnace at a predetermined position by controlling the temperature and the pressure of the supplied oxygen;
• achieving control of the stirring strength by varying the oxygen pressure while changing the oxygen temperature so as to maintain the oxygen flow rate at a given level;
• and, achieving control of the oxygen flow rate in the absence of variation of the stirring strength by varying the oxygen gas temperature and maintaining pressure of the oxygen unchanged.