In order to increase the productivity, the gas bottom blowing technique has been widely applied to mix molten iron/slag inside the ironmaking smelter. The main function of the technique is to increase the interface area between slag and iron, then to enhance the rate of the smelting reduction. In this study, the simulated experiments of the ironmaking smelter using water model were conducted to investigate the mixing degree of molten iron/slag under different gas bottom blowing conditions. In the experiments, the major parameters of the gas bottom blowing were the inside diameter of tuyere (6.0 to 15.0 mm), the total gas flow rate (320 to 480 normal liter/min), the placement of the bottom blowing tuyeres, and the stirring energy. In the water model, water and spindle oil were selected to be the substitute of liquid iron and molten slag, respectively, inside the smelter. Additionally, thymol was used as the tracer of mass transfer between the water phase and the oil phase. Based on the mass transfer rate equation with the analyzed data of thymol concentration during experiments, the mixing degree could be distinguished for different blowing conditions.In this study, it was found that the mixing degree of water and oil in the case of 10.0 mm inner diameter tuyere was higher than those of other size tuyeres under the same gas flow rate via 4 tuyeres. Also, the mixing degree increased with increasing the total gas flow rate. Additionally, the mixing degree in the case of 4 tuyeres in the square-corner placement was higher than that in the triangle-corner-center placement at the same tuyere size and total gas flow rate. If considering both mixing efficiency and the gas consumption, the best choice of blowing condition would be four tuyeres of 10.0 mm diameter in the square-corner placement under the total gas flow rate of 320 normal liter/ min.

A water model was adopted to physically simulate the bottom gas stirring inside an ironmaking smelter. The water model experiments were conducted to investigate the erosion of the bottom refractory lining near the tuyere tip under different gas bottom blowing conditions. In experiments, the major parameters are the gas flow rate, and the inside diameter and placement of bottom blowing tuyeres.The purpose of this study is to provide a design and operation reference of the gas bottom blowing system for CSC's Ironmaking Smelter. A transparent acrylic water model, which is 60% of the actual furnace's size, is used to study the erosion of the bottom refractory lining near the tuyere tips. The experiments suggested that the erosion rate of specimens near the tuyere tips reduced with a decrease in the gas flow rate. In the case of the triangle-corners-center placement of four bottom blowing tuyeres, the lowest erosion rate of boric acid specimens was found at a 15 mm tuyere size. In the case of the square-corners placement of four bottom blowing tuyeres, the lowest erosion rate of boric acid specimens was found at a 10 mm tuyere size. With the same blowing conditions, the erosion rate appears to decrease with a decrease in tuyere numbers. It was shown that the erosion rate of the square-corners placement case was lower than that of the triangle-corners-center at the same bottom blowing condition. The results imply that the conditions for the lowest erosion rate of specimens is a bottom blowing gas flow rate for each tuyere of 80 L/min, a tuyere inner diameter of 15.0 mm and three bottom blowing tuyeres, all of which should be in the range of the experimental parameters described above.

This study uses a water model experiment to investigate the effects of gas bottom blowing conditions on fluid flow phenomena and the mixing time of molten iron within an ironmaking smelter. Our experimental setup adopted four tuyeres in a square-corner placement. The parameters for trials include bottom-blowing tuyere size (7:515:0mm) and the bottom blowing gas flow rate (320480NL/min). Experimental results show that the bubble size decreased and the invading depth became deeper as the tuyere size decreased and the total gas flow rate increased. Consequently, the spout height of the liquid surface became higher. The results of the mixing experiment indicate that under any bottom blowing gas flow rates, the 10.0mm tuyere has the shortest mixing time. Except for the 7.5mm tuyere, the 10.0mm, 12.5mm, and 15.0mm tuyeres had shorter mixing times and better mixing effects as the gas flow rate increased. Therefore, the best combination for mixing iron phase in a smelter is to use a 10.0mm tuyere and a gas flow rate of 480NL/min, which has the appropriate intensity of the total blown energy and the degree of stirred liquid bath. [doi:10.2320/matertrans.M2010104