Hydrated lime is calcium hydroxide, commonly known, as the country has increased its air pollution control, various industrial companies also invested a lot of efforts in environmental management, due to the lime has a higher cost in terms of environmental desulfurization, the use of quantity every year increments. For the desulfurization, slaked lime itself is due to the base, and therefore very widely used in the field of environmental protection, desulfurization, desulfurization by spray drying in many places, it is a relatively new FGD technology, the process is especially suitable for plant transformation and peaking power plants applications. Spray drying desulfurization by-product is calcium sub *, *, calcium, a mixture of fly ash and unreacted calcium oxide. Due to the presence of CaO originally used only for landfill, but now also has a new building materials gradually purposes. Its use in the spray drying lime slurry is atomized into fine droplets absorber to remove SO2. Water is evaporated by the flue gas, the flue gas in the absorption tower so that there is sufficient residence time of SO2 and other acid gases such as SO3, HCl and other simultaneously and calcium hydroxide, calcium generating sub * / * calcium and calcium chloride. Reaction between S02 and slaked lime as follows: Ca (OH) 2 + SO2 = CaS03 + H2O CaSO3 + 1 / 2O2 + 2H2O = CaSO4 · 2H2O