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Comprehensive Kinetic, Thermodynamic, and Response Surface Analysis of Selective Neodymium Leaching from Slag-Residue Bauxite Using Sulfuric Acid
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DOI：10.1007/s40831-026-01470-7.png)
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Abstract
En 中文
This study presents an integrated experimental, kinetic, and thermodynamic investigation of neodymium (Nd) recovery from washed slag-residue bauxite (WSRB) using sulfuric acid. The effects of pH (0.5-5), temperature (30-90 degrees C), and time (0.5-3 h) were systematically examined, and process optimization was performed using Response Surface Methodology (RSM) based on Central Composite Design. Under strongly acidic conditions (pH < 0.5) and elevated temperature (90 degrees C), Nd dissolution reached 98.1%, whereas Al co-leaching remained below 10%, demonstrating high selectivity. Statistical modeling produced an excellent fit (R-2 = 0.97), and the predicted optimum (pH 0.30, T = 105.7 degrees C, t = 2.72 h) was validated experimentally with 99.6% Nd recovery (0.4% deviation). Kinetic evaluation via the shrinking core model revealed an equilibrium-controlled leaching mechanism, with forward rate constants increasing from 0.1948 to 1.3810 s(-1) as temperature increased from 303 to 363 K. The activation energy (Ea = 26.45 kJ mol(-1)) confirms chemically activated dissolution. Thermodynamic analysis yielded positive enthalpy (Delta H = + 26.45 kJ mol(-1)) and positive entropy (Delta S = + 81.68 J mol(-1) K-1), indicating an endothermic reaction with increased disorder. Negative Gibbs free energy values (- 785.3 to - 3235.8 J mol(-1)) at elevated temperatures confirm increasing spontaneity. Post-leaching characterization identified quartz as the dominant phase (87.3 wt% SiO2), validating selective dissolution of Nd-bearing species. These results demonstrate the viability of sulfuric acid leaching supported by kinetic-thermodynamic insights for efficient and sustainable Nd recovery from industrial bauxite by-products.
Keywords:
Neodymium leaching
Bauxite
Kinetics
Thermodynamics
RSM
Sulfuric acid
Journal
J
IF:
3.2
Papers:
297
Citations:
2.8K
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