Patent ID: 6432165
Filing Date: 2002-08-13
Classification: C21C

Abstract:
Method for blowing combustible gases into a free space above a molten metal located in a metallurgical vessel which is under vacuum, by means of a cooled lance, comprising the steps of:b) adding solid particles to the gas according to a desired procedure; c) guiding a second gas flow out to beyond the end of the central pipe via an annular chamber arranged coaxially with respect to the central pipe so that the second gas flow surrounds the first gas flow; d) on leaving the end of the central pipe which is in the form of a Laval nozzle, the first gas flow re-expands and comes into contact with the surrounding second gas flow, is deflected by at least one of the second gas flow and an inner wall of an encasing pipe of the lance, which encasing pipe converges conically in the direction of gas flow, whereby the first gas flow is bundled outside the lance, downstream thereof, the first gas flow guided through the central pipe being a fossil-fuel gas and the second gas flow guided through the annular chamber being oxygen, the process including setting the fuel gas and the oxygen in approximately stoichiometric ratios and setting dynamic pressures pB/poat 1.4 to 1.8/1 where pB=pressure of the fuel gas, and po=pressure of the oxygen.