Effect of Calcination Conditions on the Reactivities of Burnt Dolomite with Water and Molten FeO-SiO₂ Slag

Abstract

In steelmaking processes, slag formation in a converter is always a matter of interest. This study is focused on two kinds of dolomite produced at different areas in Japan. These dolomites were calcined in a laboratory furnace over the temperature range from 1073 K to 1473 K for two hours, and served to immersion test into water and molten FeO-SiO₂ slag.
The reaction behavior of burnt dolomites with water and the molten slag is characterized by two stages. One is the disintegration stage of dolomite, which is controlled by cracks due to the shrinkage of thermal decomposition during calcination. The other is the dissolution stage of each disintegrated particles. The important factor of this stage is the clearances among micro grains produced by the reaction during calcination.
The disintegration stage is affected by grain size of raw dolomite and calcination temperature, but, the effect of grain size did not appear so clear in the slag because of intensive erosion ability of the slag.
The dissolution rate decreases with an increase of the calcination temperature in the same way in both cases of the reaction with water and with the molten slag. This is because the micro grain combines with adjacent one to grow larger.