Gypsum as a Feedstock for Low-Cost, Decarbonized Portland Cement and Sulfuric Acid

Abstract

Production methods for cement and sulfuric acid are likely to change in the era of decarbonization. Cement is responsible for 8% of world carbon dioxide (CO₂) emissions and urgently needs to be decarbonized, while sulfuric acid (H₂SO₄) is produced from elemental sulfur, a fossil fuel byproduct whose supply may dwindle over time. Here, we perform a technoeconomic analysis of processes to coproduce Portland cement and sulfuric acid from gypsum via fossil-free variations of the once-prevalent Müller–Kühne (MK) process. With credit for coproduced sulfuric acid, a sulfur-driven variant of the MK process could achieve cost parity with limestone-derived cement ($40/t clinker) with dramatic (95–99%) reductions in the emission intensity. While MK process variants would saturate sulfuric acid markets well before they dominate world cement demand, these processes could simultaneously support a circular sulfur economy through valorization of gypsum waste and constitute a pathway to cost-effective decarbonized cement from a limestone-free feedstock.