To apply coal fly ash to the remediation of heavy-metal-contaminated soil, an alumina–silica nano-amendment (ASNA) was synthesized from coal fly ash and was used for the immobilization of lead and zinc in contaminated soil. The investigation on the synthesis of the ASNA shows that the ASNA can be obtained under a roasting temperature of 700 °C, a ratio of alkali to coal fly ash of 1.2:1, and a molar ratio of silicon to aluminum of 1:1. The ASNA could increase the soil pH and cation exchange capacity (CEC) and decrease the bioavailability of Pb and Zn. When the ASNA addition increased from 0 to 2%, the bioavailability (extracted by CaCl₂) of Pb and Zn decreased by 47% and 72%, respectively. Moreover, the addition of the ASNA facilitated the transformation of Pb from a reducible fraction to oxidizable and residual fractions and Zn from an exchangeable fraction to a residual fraction. The correlation analysis and cluster analysis verify that the ASNA modulates the chemical speciation of heavy metals by increasing the soil’s CEC and pH, thereby immobilizing heavy metals. It is expected that this study can provide a new method for the remediation of Pb- and Zn-contaminated soil.

Granite-hosted uranium ores exhibit heterogeneous mineral assemblages and complex pore structures, which may restrict lixiviant accessibility and uranium dissolution during acid leaching. This study investigated a mixed nonionic surfactant system comprising OP-10 and Tween 80 for sulfuric acid leaching of a granite-hosted uranium ore containing 787.5 ppm U. Mineralogical characterization, surface-tension measurements, stirred-leaching and column-leaching experiments, and kinetic modeling were conducted to evaluate the leaching performance. The ore was dominated by quartz, feldspar, and other aluminosilicate minerals, with a heterogeneous pore network. OP-10 exhibited a greater surface-tension-reducing ability than Tween 80, and a 3:1 OP-10/Tween 80 volume ratio was selected. In stirred-leaching tests at 30 °C, a liquid-to-solid ratio of 5.0 mL·g⁻¹, and 20 g·L⁻¹ H₂SO₄, uranium recovery after 10 h increased from 72.4% in the H₂SO₄ system to 87.8% in the mixed-surfactant system. Separate kinetic experiments were conducted at 20 °C and a liquid-to-solid ratio of 2.5 mL·g⁻¹. After 31 d of column leaching, cumulative uranium recoveries were 74.0% and 92.6% for the H₂SO₄-only and mixed-surfactant columns, respectively. Nonlinear first-order fitting yielded apparent rate constants of 0.04176 and 0.06480 d⁻¹, respectively. These column results are descriptive observations because only one independent column was tested per condition. Kinetic model comparisons did not establish a unique rate-controlling mechanism, and the possible contributions of interfacial behavior and solution transport remain to be verified. This study provides experimental evidence for evaluating mixed nonionic surfactants in granite-hosted uranium leaching and offers a basis for further optimization of surfactant-assisted leaching conditions for complex hard-rock uranium ores.