Exploring phosphorus dissociation kinetics in HCl-leached moderate-grade phosphate ores: Towards high-quality dicalcium phosphate production

Reaction kinetics is crucial for understanding process mechanisms and plays a key role in the recovery of phosphorus extraction, providing essential insights for optimization and scaling up, which directly impact profitability and engineering design. This article focuses on the comprehensive study of the reaction kinetics involved in phosphorus extraction from apatite mineral using prepared HCl, emphasizing its significance for efficient resource utilization and process enhancement. The impacts of acid concentration, solid-to-liquid ratio, particle size fractions, agitation rate, and temperature on the dissolution rate were meticulously evaluated. The dissolution kinetics of phosphorus extraction from apatite using heterogeneous reaction models, identifying the best-fitting equation for experimental data. A P₂O₅ extraction rate of 99.93 % was achieved at 14 °C with (+0.063–0.15) mm particles after 90 s. The variance coefficient (CV) of the typical sample was calculated to be 112 %. Shrinking Core Models (SCMs) were employed to determine the rate-controlling phase of the leaching process, leading to a semi-empirical kinetic equation for P₂O₅ leaching. The activation energy was found to be 15.88 kJ/mol using the Arrhenius equation. Energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) analyses confirmed silica residue. This work sheds light on phosphorus extraction kinetics, aiming at optimizing the process conditions, designing efficient reactors, and assessing the operation’s economic viability.