Sedimentation-Based Separation and Purification of Solid Industrial Waste: A Case Study of Phosphogpusym

The continuous accumulation of solid industry waste, such as phosphogypsum, has emerged as a global environmental hazard and a significant obstacle to achieving a green and sustainable industry. To convert this industry waste to reusable resources, the development and implementation of simple and cost-efficient purification techniques is crucial. A sedimentation-based separation approach was developed to achieve this objective. Through a sedimentation process, a suspension of phosphogypsum particles is transformed into three distinct phases: a supernatant liquid, a concentrated slurry, and a solid precipitate. These phases primarily consist of soluble salts, a mixture of oxides and organic matter, and calcium phosphate dihydrates mixed with calcium phosphate, respectively. Through a sedimentation process, calcium sulfate dihydrate concentration can be significantly enhanced from 87.45 to 91.60% and further improved to 95.72% by repeating the sedimentation process three times. The various components obtained from this process can be effectively reused as mineral resources, soil amendment, and industry gypsum. The sedimentation process is expounded upon using both the classical mechanics model and Stokes' law. To foster a seamless industrial application, we have also designed a continuous settling skittle and a trail setup for industrial treatment of phosphogpysum. This innovative technique holds immense promise for its broader application, especially within but not limited to the phosphoric acid industry.