Effect of Gas Bottom Blowing Conditions on Mixing of Molten Iron inside an Ironmaking Smelter

To aid efficient use of the gas flow rate for a smelting reduction furnace, this study investigates the effect of gas bottom blowing and stirring on the mixing time of the molten iron phase. In this study, transparent acrylic is used to construct a water model, which is 60 % as big as the original experimental melting reduction furnace of the China Steel Corporation. The mixing time of the molten iron phase in the water model is measured by using gas bottom blowing and changing the number of tuyeres (from three to five), the tuyere placement, the tuyere size (6.0– 15.0mm), and the gas flow rate per tuyere (80–120NL/min). The mixing trials adopt KCl as an indicator and use water filtrated using reverse osmosis (RO) in place of liquid iron to investigate the effect of gas bottom blowing conditions on mixing of the molten iron phase. The experimental results indicate that in the cases of four tuyeres in the square-corner and triangle-corner-center placements, 10.0mm tuyeres yield the shortest mixing time (and thus the best mixing effect) under different total gas flow rates. In the case of five tuyeres in the square-corner-center placement, 10.0mm tuyeres also have the shortest mixing time under total gas flow rates of 400NL/min and 500NL/min. However, 12.5mm tuyeres have the shortest mixing time under a total gas flow rate of 600NL/min. In addition, in the case of three tuyeres in the triangle-corner placement, 12.5mm tuyeres have the shortest mixing time under different total gas flow rates. When the gas flow rate per tuyere is 80NL/min, the fewer the tuyeres, the shorter the mixing time. Depending on tuyere placement, some of the energy injected by the gas may be counteracted. For example, when a bottom-blowing tuyere exists in the center, the gas injection from that tuyere may be counteracted by that of adjacent tuyeres such that energy dissipates. In contrast, a tuyer