Decomposition of Limestone in Hot Metal at 1300 °C

Decomposition and dissolution of cylindrical limestone samples (ø16 mm × 50 mm approximately) in hot metal at 1300 °C are experimentally studied. The cross section of burned limestone is determined by using image processing and then the lime layer thickness is determined. The three layers of the cross section of burned sample are analyzed by using SEM, and the change of the Fe content along the radial direction is also analyzed. A kinetic model is established to characterize the calcination of limestone in hot metal. The results show that there are three distinct layers on cross section of burned limestone: a reacted layer in the outside, a burned lime layer in the middle, and an unburned limestone core in the inside. Heat transfer is the control step for limestone calcination in hot metal. Fe can be oxidized by carbon dioxide from limestone calcination, and ferrous oxide can permeate into burned lime layer along the radial direction of sample. The kinetic model for limestone calcination can be used to predict limestone conversion rate in hot metal.