This study investigates an integrated CO2 mineral carbonation process that utilizes flue gas-derived CO2, ammonia, and 

flue gas desulfurization gypsum (FGDG)—a byproduct of desulfurization processes—for the co-production of calcium 

carbonate (CaCO3) and ammonium sulfate ((NH4)2SO4). A process design is conducted for a 300,000 tonne/yr commercial-scale

plant, modeling the entire FGDG-NH4OH-CO2 system from pretreatment to crystallization. Following this, a 

detailed techno-economic assessment (TEA) is performed, calculating the discounted cash flow based on comprehensive 

economic parameters. Under the base case scenario, the annual Levelized Net Profit (LNP) is estimated to be 3,915,064 

USD/yr, which corresponds to 43 USD per ton of fixed CO2. Additional case studies consider various scenarios such as 

the free provision of FGDG, variations in ammonia pricing, and inclusion of carbon credit pricing, indicating a potential 

increase in profitability of up to 241%. Sensitivity analysis identifies the selling price of ammonium sulfate and utility 

costs as the most influential variables affecting profitability, confirming that ensuring raw material price stability and 

improving energy efficiency are critical strategies for enhancing economic performance. Additional sensitivity analyses 

are performed to account for uncertainties associated with the Aspen Process Economic Analyzer (APEA) and potential 

scale-up-induced yield deviations, confirming the robustness of the main conclusions. The results demonstrate that the 

FGDG-NH4OH-CO2 system can achieve both economic feasibility and effective CO2 mitigation, providing strategic 

insights for industrial deployment under diverse market and policy conditions.