Clean and Efficient Utilization of Symbiotic Elements in Wet-Process Phosphoric Acid: Study on High-Value Process of Aluminum

In the production of high-purity industrial phosphoric acid by wet process, the symbiotic elements are often treated as solid or liquid waste. This causes a waste of natural resources. In this work, a new wet-process phosphoric acid (WAP) purification route was proposed. In particular, the regeneration process of extractant was optimized, and the recovery process of aluminum was studied in detail (including stripping and crystallization). The effects of operational parameters and composition on the stripping behavior were investigated by single factor experiment and relevant analysis. Dissolution equilibrium date indicated the mother liquor could be circulated when the crystallization temperature was 298.15 K. Aiming to yield the purified extractant, the theoretical stages of stripping were simulated by plotting McCabe-Thiele diagram. Two-stage countercurrent extraction was carried out through a series of cascade experiments, indicating that over 95% Al3+ was stripped into aqueous phase. Furthermore, Al3+ in WPA was successfully changed into ammonium aluminum sulfate by this process, and it had higher purity than industrial grade. The results provide a basis for the high-quality utilization of associated resources in WPA.