This project is a rotary kiln flue gas desulfurization project of Nandan County Jilang Indium Industry Co., Ltd. It was successfully operated for 72 hours on September 21, 2017, and was successfully accepted on the 21st. Geelong company's existing flue gas treatment, the generated by-product gypsum is directly landfilled, which is no longer suitable for the increasingly severe environmental protection situation. For this reason, our company uses zinc oxide desulfurization process to transform it, and its by-product is zinc sulfite, which can be directly reused in its production process, which solves the problem of subsequent treatment of by-products. The total flue gas volume of the project is 135,000m3/h, and the SO2 concentration is 8500mg/Nm3. The front end is designed with a water washing tower, and the back end is designed with a two-stage desulfurization tower. The whole system adopts PLC+touch screen control mode. The SO2 concentration of the flue gas at the outlet of the desulfurization tower is less than or equal to 200mg/m3 .