Influence of O2 Content in Circulating Flue Gas on Iron Ore Sintering Original Research Article

Circulating flue gas can reduce the emission of flue gas, and furthermore, it can reuse the waste heat effectively in the sintering process. Compared with conventional sintering, O2 that gets through the sintering bed decreases because of substituting circulating gas for air. The influences of O2 content on sintering process are studied through simulating the flue gas circulation sintering with artificial gas. It shows that, with the reducing of O2 content in circulating gas, the combustion speed of fuel decreases and incomplete combustion degree increases, which makes the flame front fall behind the heat front and reduces the heat utilization efficiency of fuel. The ultimate result is that the temperature of sintering bed decreases and the liquid phase reduces. In addition, the reducing atmosphere is strengthened because of flue gas circulation, which makes the magnetite increase yet calcium ferrite reduce gradually. Because the content of calcium ferrite with good strength reduces, the sinter yield and tumble strength decrease. To ensure the sinter index, the favorable O2 content of circulating flue gas is no less than 15%.