Recycling, reusing and environmental safety of industrial by-product gypsum in construction and building materials

With the rapid advancement of industrial production, the substantial accumulation of industrial by-product gypsum containing high salinity, acidity/alkalinity, and heavy metals are currently causing widespread ecological damage on a global scale. Based on the different industrial production processes, industrial by-product gypsum can be divided into various types. This study summarized industrial by-product gypsum into eight types (flue gas desulphurization gypsum (FGDG), phosphogypsum (PG), titanium gypsum (TG), salt gypsum (SG), fluorgypsum (FG), nitro gypsum (NG), citric acid gypsum (CAG) and borogypsum (BG)). Subsequently, the chemical, physical properties and annual productivity associated with these eight types of industrial by-product gypsum was investigated. Next, a study about the industrial by-product gypsum's recycling and reusing was carried out in the realm of construction and building materials (building materials, filling materials and soil conditioners). Then, the influence of the type and content of industrial by-product gypsum on key properties indicators was conducted. Based on the different effects of varying contents of industrial by-product gypsum in construction and building materials, the industrial by-product gypsum with various contents was classified into three levels for sulfate activator, supplementary cementitious material, and primary component, respectively. Ultimately, the leaching property of industrial by-product gypsum was analyzed and its environmental safety was evaluated. Additionally, this study proposed a series of suggestions aimed at enhancing the efficient recycling and reusing of industrial by-product gypsum resources.