Optimization of Cyclone-Type Rotary Kiln Reactor for Carbonation of BOF Slag

Abstract

Mineral carbonation of the basic oxygen furnace (BOF) slag produced in the steel-making process not only provides an effective approach for carbon dioxide storage, but also stabilizes the slag such that it can be reused as a construction material. Generally speaking, carbonation performance improves as the time for which the carbon dioxide resides within the reactor increases. This research proposes a method to increase the residence time of carbon dioxide in the cyclone converter slag carbonization kiln by adjusting the inclination angle and length of the feed pipe. Therefore, it has the same effect of increasing the flow path length of the cyclone in the reactor. The optimal values of the inclination angle and length of the gas inlet tube are determined using the robust Taguchi design method. Computational fluid dynamics simulation results show that the optimized reactor design increases the average residence time of carbon dioxide gas by 60.4%, compared with the original rotating reactor design with a straight (non-cyclonic) flow path. Moreover, the experimental results show that the optimized design increases the carbon dioxide storage capacity from 12.15 g per kilogram of BOF slag in the original rotary kiln reactor to 16.00 g in the re-designed reactor.