Structurally controlled synthesis of synthetic gypsum derived from industrial wastes: sustainable approach

BACKGROUND The article demonstrates the possibility of processing spent sulfuric acid and limestone waste into high-quality synthetic calcium sulfate dihydrate. RESULTS A comprehensive technological scheme for the production of synthetic gypsum from industrial waste was proposed. Mathematical models of the main technological stages were obtained. In the process of acid processing, at the stage of separating gypsum from the mother liquor, a filtrate was formed containing ions such as Na+, K+, Mg2+ and SO42-, which are some of the main ions necessary for plant growth. A positive effect was found when using the filtrate as fertilizer. CONCLUSIONS Optimal values of synthesis parameters that allow one to obtain crystals of the maximum size were determined. A positive effect when using the filtrate as fertilizer was found. These results mean that it is possible to obtain a technology for gypsum with a closed production cycle (waste-free technology) derived from waste limestone and spent sulfuric acid. (c) 2021 Society of Chemical Industry (SCI).