The Utilization of Fgd Gypsum for Removing Hms from Smelting Acid Wastewater Via Vulcanized Precipitate

Abstract

This study investigates an environmentally friendly technology that utilizes flue gas desulfurized gypsum to treat acidic wastewater produced by flue gas acid production. The reduction roasted product (CaS) of FGD gypsum is used as a vulcanizing agent and can effectively replace the current commonly used vulcanizing agent. It can react with clean acid to form H2S gas, and no other impurity ions are introduced when removing heavy metals (HMs) in acidic wastewater. The intermediate products can be cycled. A series of laboratory experiments is conducted to explain the preparation of H2S gas and its suitability for HMs removal. The results show that the production rate of H2S is as high as 94%. A kinetic model of its reaction process was established and the reaction process is mainly affected by the diffusion process. The removal rate of HMs such as As and Cd in acidic wastewater is as high as 99.9%. The treated acidic wastewater and calcium sulfate can be recycled. The honeycomb structure of the roasted product (CaS) is very suitable for the preparation of H2S, which has the characteristics of fast gas production and high efficiency. It provides a new closed-loop recycling for FGD gypsum.

Keywords: Flue gas desulfurization gypsum, Vulcanized precipitate, Acidic wastewater, Recycling