Co-preparation of calcium sulfoaluminate cement and sulfuric acid through mass utilization of industrial by-product gypsum

• Published in: Journal of cleaner production 2020-08, Vol.265, p.121801, Article 121801
• Main Authors: Wu, Shuang, Yao, Yonggang, Yao, Xingliang, Ren, Changzai, Li, Jingwei, Xu, Dong, Wang, Wenlong
• Format: Article
• Language: English
• Subjects: Compressive strength; Decomposition; Life cycle assessment; Mineral formation; Sulfur dioxide concentration
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2020.121801

Industrial by-product gypsum is a waste by-product containing mostly calcium sulfate. Problems related to its storage and utilization have become a bottleneck restricting the development of various industries. The authors investigated the feasibility of co-producing calcium sulfoaluminate cement and sulfuric acid through the mass utilization of industrial by-product gypsum. The CaSO4 and CaO derived from the partial decomposition of industrial by-product gypsum are used to form calcium sulfoaluminate clinker minerals, and the SO2 released during the production of calcium sulfoaluminate clinker is collected and transformed into sulfuric acid. The experimental results show that calcium sulfoaluminate cement can be prepared using the decomposition of industrial by-product gypsum, and its mineral formation, compressive strengths, and microstructure are satisfactory. According to the theoretical calculation, the concentration of SO2 released during the production of calcium sulfoaluminate clinker could reach 7.55% thereby meeting the required concentration for the preparation of sulfuric acid. A life cycle assessment also showed that the co-production of calcium sulfoaluminate cement and sulfuric acid using the decomposition of industrial by-product gypsum has a lower environmental impact than the conventional production process. In this study, a promising and environmentally friendly method for the mass utilization of industrial by-product gypsum, effectively eliminating the environmental contamination caused by its accumulation, is described. [Display omitted] •CSA cement was prepared entirely using IBP gypsum as CaO and SO3 sources.•The weight fraction of IBP gypsum in CSA cement raw materials was above 70%.•Co-preparation of CSA cement and sulfuric acid was proved feasible.•Co-preparation process was proven to be environmentally friendly through LCA.