Carbonation of gypsum from wet flue gas desulfurization process: experiments and modeling.

In this paper, waste gypsum from wet flue gas desulfurization (WFGD) mixed with NH·HO was applied for CO absorption in the solid-liquid-gas phase system. The effects of operation temperature, CO flow rates, and ammonia-to-gypsum ratio on carbonation process were discussed. Meanwhile, a model for CO absorption in the suspension of WFGD gypsum and ammonia was established. The results indicate that higher temperature favors the reaction, and WFGD gypsum conversion can be achieved above 90% even at lower ammonia-to-gypsum ratio, while CO conversion reaches 90% and ammonia utilization is up to 83.69%. The model fits well with the experimental results at various CO flow rates and predicts the concentration distribution of the main species, including CO absorbed, NHCOO, and HCO.