Abstract:Phosphogypsum (PG), a by-product of phosphoric acid production, is generated in large quantities globally, with China being the leading producer. The annual production of PG in China has reached 75 million tons, and the global cumulative accumulation has exceeded 6 billion tons. The massive stockpiling of PG not only occupies land resources but also poses significant environmental risks such as water, soil, and air pollution, thereby hindering the sustainable development of the phosphorus chemical industry. However, due to its physicochemical properties being similar to natural gypsum, PG has potential for resource utilization, particularly in the construction industry, where it can be used to produce various building materials. This study focuses on the calcination processes of PG, aiming to explore current methods for its conversion into valuable building materials such as β-hemihydrate gypsum (β-HPG) and anhydrite II. The calcination of PG involves three critical stages: dehydration, decomposition, and phase transformation. Temperature control is essential in each stage to determine the final product""s properties. Traditional calcination techniques, including kettle calcination and rotary kiln calcination, have been widely used but are limited by high energy consumption, uneven heat transfer, and large equipment investments. Advanced methods like fluidized bed calcination and two-step fluidized bed calcination have demonstrated superior efficiency and product stability. These methods utilize low-temperature slow calcination, which improves the uniformity of the product and reduces energy consumption. The calcination-acid leaching combined treatment significantly enhances the whiteness and purity of PG, making it suitable for high-value applications. The results indicate that optimized calcination processes can effectively convert PG into high-quality building materials. For instance, β-HPG produced through fluidized bed calcination exhibits excellent hydration activity and mechanical properties, making it a viable alternative to natural gypsum in construction applications. Furthermore, the integration of additives such as fly ash, lime, and foaming agents in β-HPG-based composites improves their performance, offering new pathways for the resource utilization of industrial by-products. Innovative approaches such as calcination-acid leaching combined treatment have been developed to enhance the quality and efficiency of PG utilization. This method involves calcining PG at 600 °C for 70 minutes, followed by acid leaching with 1.5 mol/L sulfuric acid at 90 °C for two hours. This process significantly increases the whiteness of PG from 51.5% to 92.7%, making it suitable for high-value applications such as PVC fillers and plastering materials. The study also highlights the importance of controlling calcination temperature and time to optimize the transformation of PG into valuable products. In conclusion, the study highlights the potential of advanced calcination technologies in addressing the challenges associated with PG utilization. The development of low-energy, high-efficiency calcination processes, coupled with innovative purification techniques, can significantly enhance the value and applicability of PG in the construction and industrial sectors. Future research should focus on further optimizing these processes, exploring new applications, and developing integrated systems for large-scale PG resource utilization, thereby contributing to the sustainable development of the phosphorus chemical industry.