Solvent extraction is a broadly employed method for removing impurities from wet-process phosphoric acid (WPA). However,

the raffi nate acid generated by this method remains underutilized due to its high viscosity and elevated metal impurity (Fe, Al,

Mg) content and nonmetallic impurities (S, F), resulting in resource waste. This study employs P-15 as the extractant to purify

raffi nate acid and introduces an innovative stripping–crystallization process for the separation and recovery of Al 3+ and Mg 2+ ,

yielding high-value products. A comparative analysis of various stripping agents identifi ed a sulfuric acid solution containing

ammonium sulfate as the optimal system. Under the optimized conditions (temperature: 303.15 K, organic–aqueous phase

ratio (O/A): 1:1, sulfuric acid concentration: 30 wt.%, reaction time: 30 min), the stripping effi ciency reached its optimal

value. Theoretical stage calculations using the McCabe–Thiele method and cascade simulation determined that a two-stage

countercurrent operation is required. To address crystallization inhibition caused by aluminum–fl uoride complexes, silicon

or boron (introduced as sodium silicate or borax) was incorporated to form more stable SiF 6

2− or BF 4

- complexes, facilitating

Al 3+ release and its subsequent precipitation as NH 4 Al(SO 4 ) 2 ·12H 2 O. Further addition of ammonium sulfate enabled the

formation of (NH 4 ) 2 Mg(SO 4 ) 2 ·6H 2 O. This study provides an effi cient and environmentally friendly process for the valorization

of raffi nate acid from WPA production, off ering signifi cant industrial application potential and environmental benefi ts.