来源：ScienceDirect
Weathered crust elution-deposited rare earth ores (WREOs) are an important source of medium and heavy rare earth elements in China. However, the conventional ammonium sulfate leaching process is often hindered by clay mineral swelling, pore-structure deterioration, and associated mass transfer resistance. In this study, potassium humate (KA) was introduced as a leaching aid to enhance rare earth extraction from WREOs. The effects of particle size, KA concentration, and temperature on leaching behavior were systematically investigated. Leaching kinetics were analyzed using the shrinking core model, while column mass-transfer characteristics were evaluated based on plate theory. In addition, a coupled reactive transport model was developed to simulate the leaching process. The results show that under optimal conditions (particle size < 0.075 mm, 0.08 mol/L (NH4)2SO4, 0.1 g/L KA, liquid-to-solid ratio of 2:1, flow rate of 0.5 mL/min, pH 6.65, and 298 K), the rare earth leaching efficiency reaches 97.30%, which is 7.17% higher than that achieved with ammonium sulfate alone. In addition, the leaching duration is shortened from 585 to 284 min (a reduction of 301 min). Kinetic analysis indicates that the intraparticle diffusion controls leaching process, with an apparent activation energy of 16.12 kJ/mol. A kinetic model incorporating the effects of temperature, particle size, and KA concentration is established. Mass-transfer analysis reveals that the theoretical plate height (HETP) reaches a minimum at a KA concentration of 0.1 g/L, indicating the highest mass-transfer efficiency. The simulation results agree well with the experimental data (R2 > 0.98) and successfully reproduce the spatiotemporal evolution of the rare earth concentration front. Collectively, these results suggest that an appropriate KA concentration facilitates liquid transport and rare earth release, whereas excessive KA may increase mass-transfer resistance through enhanced humate aggregation. These findings provide a quantitative basis for optimizing the green and efficient extraction of rare earth elements from WREOs.