Abstract: In a method of controlling a blast furnace wherein iron ore is reduced to form pig iron and there being at least one reactor used for heating a reducing gas which reducing gas is introduced to at least one tuyere, the improvement being the steps of adjusting the composition and the temperture of the reducing gas in order to control at least one of the following: coke rate, productivity of the blast furnace, temperature and/or silicon content of the pig iron, and temperature of the top gas. Preferably, the reactor is a plasma torch and the temperature of the reducing gas is in the range of 1500.degree.-2800.degree. C. The coke rate is predetermined at a value of 50-350 kg/mt of pig iron and preferably at 80-200 kg/mt of pig iron produced.

Abstract: A tuyere for injecting hot reducing gases into a furnace is provided with an inlet pipe and a plasma oven whose gas outlet axis is inclined to the longitudinal axis of the tuyere. The angles which the outlet axis of the plasma oven and the inlet pipe form with the said longitudinal axis are such that the longitudinal axis is parallel to the vector sum of the amount of movement of the gases from the plasma oven and the inlet pipe respectively .