The effect of magnesium content and roasting process on the structure and desulfurization activity of slaked lime derived from limestone

The development of industrial slaked lime with high a high specific surface area and thus improved desulfurization performance has recently attracted great attention in the field of dry desulfurization. In this paper, the structural evolution process from limestone to slaked lime was investigated, and the influence of magnesium content and roasting process on the specific surface area and desulfurization performance of the final slaked lime was revealed. The results showed that the roasting process, but not the magnesium content, plays a key role in achieving a high specific surface area (>40.00 m2/g) of slaked lime. The slightly overburning lime with a slightly reduced activity level facilitates the dispersion of the slaked lime particles, increases their specific surface area and improves the desulfurization performance. On the other hand, as the magnesium content in limestone increases, the removal efficiency of SO2 will decrease significantly due to the weak reaction activity of MgO/Mg(OH)2 with SO2, even though the impure sample has a high specific surface area (51.92m2/g). In addition, in-situ DRIFTS results showed that the high concentration of CO2 in the flue gas reacted preferentially with quicklime to form CaCO3, but the slaked lime after adsorption of CO2 still had some SO2 absorption capacity. The demonstrated composition-structure evolution-performance relationships from limestone to slaked lime will provide a good guide to the production of high quality slaked lime for industrial desulfurization applications.